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CARBON DIOXIDE 



RY 

ELTON L. QUINN 

l'ROFKSV)R OK CHli NHSIKY, I. N'WCRSl I'Y OF UTAH 
AND 

CHARLES L. JONES 

FORMKKLY C'llIKF KVC.1NKKK, AMERICAN WKY ICK CORPORA I ION 




k'ciu Chomical Society 
Monograph Scries 



HOOK DEPARTMENT 
REINHOLD PUBLISHING CORPORATION 

MO WEST FOR TV-SECOND STREET, NEW YORK, U.S.A. 

1936 



COPYRIGHT, 1936, BY 
REINHOLD PUBLISHING CORPORATION 

All rights reserved 



Printed in the United States of America by 

INTERNATIONAL TEXTBOOK PRESS, SCRANTON, PA. 



GENERAL INTRODUCTION 

American Chemical Society Scries of 
Scientific arid Technologic Monographs 

By arrangement with the Interallied Conference of Pure and Applied 
Chemistry, which met in London arid Brussels in July, 1919, the American 
Chemical Society was to undertake the production and publication of 
Scientific and Technologic Mondgmphs on chemical subjects. At the 
same time it was agreed that the National Research Council, in coopera- 
tion with the American Chemical Society and the American Physical 
Society, should undertake the production and publication of Critical 
Tables of Chemical and Physical Constants. The American Chemical 
Society and the National Research Council mutually agreed to care for 
these two fields of chemical development. The American Chemical 
Society named as Trustees, to make the necessary arrangements for the 
publication of the monographs, Charles L. Parsons, Secretary of the 
American Chemical Society, Washington, D. C.; John E. Teeplc, Treasurer 
of the American Chemical Society, New York City; and Professor Gellert 
Alleman of Swart hmoiv College. Tho Trustees have arranged for the 
publication of the American Chemical Society series of (a) Scientific and 
(b) Technologic Monographs by the Chemical Catalog Company 
(Reinhold Publishing Corporation, successors) of New York City. 

The Council, acting through the Committee on National Policy of the 
American Chemical Society, appointed the editors, named at the close 
of this introduction, to have charge of securing authors, and of consider- 
ing critically the manuscripts prepared. The editors of each series will 
endeavor to select topics which arc of current interest and authors who 
are recognized as authorities in their respective fields. The list of mono- 
graphs thus far secured appears in the publisher's own announcement 
elsewhere in this volume. 

The development of knowledge in all branches of science, and espe- 
cially in chemistry, has been so rapid during the last fifty years and the 
fields covered by this development have been so varied that it is diffi- 

3 



4 GENERAL INTRODUCTION 

cult for any individual to keep in touch with the progress in branches 
of science outside his own specialty. In spite of the facilities for the 
examination of the literature given by Chemical Abstracts and such 
compendia as Bcilstein's Handbuch der Organischen Chcinic, Richter's 
Lexikon, OstwahTs Lehrbuch der Allgemcincn Chcmie, Abegg's and 
Gmelin-Kraut's Handbuch der Anorgunischen Cliemie and the English 
and French Dictionaries of Chemistry, it often takes a great deal of time 
to coordinate the knowledge available upon a single topic. Consequently 
when men who have spent years in the study of important subjects are 
willing to coordinate their knowledge and present it in concise, readable 
form, they perform a service of the highest value to their fellow chemists. 

It was with a clear recognition of the usefulness of reviews of this 
character that a Committee of the American Chemical Society recom- 
mended the publication of the two series of monographs under the auspices 
of the society. 

Two rather distinct purposes are to be served by these monographs. 
The first purpose, whose fulfillment will probably render to chemists in 
general the most important service, is to present the knowledge available 
upon the chosen topic in a readable form, intelligible to those whose 
activities may be along a wholly different line. Many chemists fail to 
realize how closely their investigations may be connected with other work 
which on the surface appears far afield from their own. These mono- 
graphs will enable such men to form closer contact with the work of 
chemists in other lines of research. The second purpose is to promote 
research in the branch of science covered by the monograph, by furnishing 
a well-digested survey of the progress already made in that field and by 
pointing out directions in which investigation needs to be extended. To 
facilitate the attainment of this purpose, it is intended to include extended 
references to the literature, which will enable anyone interested to follow 
up the subject in more detail. If the literature is so voluminous that a 
complete bibliography is impracticable, a critical selection will be made 
of those papers which arc most important. 

The publication of these books marks a distinct departure in the policy 
of the American Chemical Society inasmuch as it is a serious attempt to 
found an American chemical literature without primary regard to com- 
mercial considerations. The success of the venture will depend in large 



GENERAL INTRODUCTION 5 

part upon the measure of cooperation which can be secured in the prepara- 
tion of books dealing adequately with topics of general interest; it is 
earnestly hoped, therefore, that every member of the various organizations 
in the chemical and allied industries will recognize the importance of 
the enterprise and take sufficient interest to justify it. 

AMERICAN CHEMICAL SOCIETY 

BOARD OV EDITORS 

Scientific Scries: Technologic Series: 

WILLIAM A. NOTES, Editor, HARRISON E. HOWE, Editor, 

S. C. LIND, WALTER A. SCHMIDT, 

F. A. LIDHURY, 
FRED C. ZEISBERG, 

ARTHUR A. NOYES, E. R. WEIDLEIN, 

JULIUS SETIKGLITZ, C. E. K. MEES, 

F. W. AVlLLARD, 

CARL S. MINER, 
W. G. WHITMAN, 
C. H. MATIIEWSON. 



PREFACE 

The writing of this book was started several years ago because we 
believed that a treatise was needed in which much of the available infor- 
mation concerning carbon dioxide should be assembled in a usable form. 
The result of this labor is now passed on to those interested in the subject, 
with a hope that it may fill this need to some extent. 

While selecting and arranging the material of which this work is com- 
posed we have aimed at a very broad treatment of the many phenomena in 
nature and industry in which carbon dioxide is an important factor. We 
have attempted to keep in mind the needs of the industrial worker, the 
research student and the general reader who is attempting to gain some 
information concerning the subject. Rapidly changing conditions, espe- 
cially in the carbon dioxide industry, have made it difficult to satisfactorily 
attain all of these objectives. ^cJiave made no special effort to paint a 
picture of the carbon dioxide industry as it exists todayj mainly because 
such ajncture would have only historical interest in a very short time. 
The attempt to put into one volume such widely divergent idcasT asThe 
natural occurrence of carbon dioxide in Yellowstone National Park, the 
treatment of skin diseases with solid carbon dioxide and the blasting down 
of coal with the liquid form, makes a well-coordinated discussion difficult, if 
not impossible. We believe, however, that our treatment is justified, 
because after all, the subject treated, is "Carbon Dioxide." 

Many persons have assisted either directly or indirectly in this project. 
Several plant executives with important industrial connections have read 
all or part of the manuscript. For obvious reasons these men have requested 
that we do not use their names in acknowledging this aid. We wish, how- 
ever, to express our gratitude to them as well as to those who so kindly 
permitted plant inspections by the senior author. 

We wish also to extend our thanks to the following persons who have 
given us exceptional aid : Dr. George Thomas, President of the University 
of Utah, who made it possible for one of us to devote one whole summer 
to this work, Dr. Walter D. Homier, Professor of Chemistry, University 
of Utah, who read the manuscript and offered many excellent suggestions, 
Dr. E. B. Auerbach, of the Tra J. Owen Organization, Inc., Chicago, who 
made a very careful review and pointed out omissions and corrections, Mr. 
Edwin Johnson of the Safety Mining Company, Chicago, who furnished 
considerable material relating to the use of carbon dioxide in the coal 
mining industry, and Mrs. Helen Y. Mackintosh of the library staff of the 
University of Utah who made the index to this volume. 

E. L. Q. 

June 29, 1935 C L> J< 

7 



Contents 



PAGE 

PREFACE 7 

CHAPTER I. THE EARLY HISTORY OF CARBON DIOXIDE 11 

The Scientific Development, 11. The Industrial Development, 14. 

CHAPTER 11. CARBON DIOXIDE IN NATURE 19 

Occurrence in the Atmosphere, 19. Occurrence in the Hydrosphere, 22. 
Occurrence in the Lithosphere, 23. The Carbon Dioxide Balance in Nature, 
29. Factors Increasing Carbon Dioxide in the Atmosphere, 29. Factors 
Decreasing the Carhon Dioxide Concentration in the Atmosphere, 31. 

CHAPTER III. PHYSICAL PROPERTIES OF CARBON DIOXIDE 34 

Density of Gaseous Carhon Dioxide, 34. Density of Liquid Carbon Dioxide, 
35. Density of Solid Carbon Dioxide, 39. Molecular Weight, 40. Molec- 
ular Volume, 40. Molecular Diameter, 40. Molecular Velocity, 41. Mean 
Free Path, ,41. Velocity of Sound in Carhon Dioxide, 41. Viscosity, 41. 
Coefficient of Diffusion, 45. Diffusion Through Solids, 46. Compressi- 
bility, 50. The Coefficient of Thermal Expansion, 53. The Equation of 
State, 54. The Specific Volumes of Gaseous, Liquid and Solid Carbon 
Dioxide, 57. The Triple Point, 57. The Critical Temperature, 59. Melting 
Point, 60. Vapor Pressure of Liquid Carbon Dioxide, 61. Vapor Pressure 
of Solid Carhon Dioxide, 61. The Equilibrium Diagram of Carbon Dioxide, 
63. Dissociation of Carbon Dioxide at High Temperature, 63. The Molec- 
ular Heat Capacity of Gaseous Carbon Dioxide, 64. The Molal Heat 
Capacity of Liquid Carbon Dioxide, 68. The Molal Fleat Capacity of Solid 
Carbon Dioxide, 68. The Latent Heat of Vaporization of Carbon Dioxide, 
68. Heat of Sublimation of Carbon Dioxide, 69. The Enthalpy of Carbon 
Dioxide, 71. The Entropy of Carbon Dioxide, 76. The Surface Tension 
of Liquid Carbon Dioxide, 77. The Crystal Form, 79. The Index of 
Refraction, 80. Adsorption, 81. The TTeat of Adsorption, 92. Solubility, 94. 
The Effect of Temperature on Solubility, 94. The Effect of Pressure on 
Solubility, 95. The Effect of Temperature and Pressure Changes Expressed 
in Pounds per Square Inch and Degrees Fahrenheit, 96. Solubility of Car- 
bon Dioxide in Water Solutions of Inorganic Compounds, 97. Solubility 
of Carbon Dioxide in Water Solutions of Carbon Compounds, 102. The 
Solubility of Carbon Dioxide in Organic Solvents, 104. Supersaturation of 
Carbon Dioxide in Liquids, 106. Liquid Carbon Dioxide as a Solvent, 108. 

CHAPTER IV. CHEMICAL PROPERTIES OF CARHON DIOXIDE 113 

Action of Carbon Dioxide on Water, 113. Carbonic Acid, 114. The Dis- 
sociation Constant of Carbonic Acid, 116. The pit of Water Solutions of 
Carbon Dioxide, 119. Action of Carbonic Acid on Calcium Compounds, 121. 
The Solubility of Calcium Carbonate in Water Solutions of Carbon Dioxide, 
122. Carbon Dioxide in Natural Waters, 124. Action of Carbon Dioxide 
on Calcium Cyanamidc, 126. Action of Carbon Dioxide on Sulfides of 
Sodium and Calcium, 126. Action of Carbonic Acid on Calcium Phosphate, 
126. Action of Carbon Dioxide Solutions on Alkaline Earth Silicates, 127. 
Action of Carbonic Acid on Magnesium Compounds, 128. Solubility of 
Magnesium Carbonate in Solutions of Carbon Dioxide, 128. Action of Car- 
bon Dioxide on Aqueous Lead Acetate Solutions, 129. The Hydration 
Action of Carbonic Acid on Starch, 131. Reduction of Carbon Dioxide by 
Hydrogen, 131. Reduction of Carbon Dioxide with Carbon, 132. Action 
of Carbon Dioxide on Metals, 133. The Manufacture of Urea, 134. 



10 CONTENTS 

PAGE 

CHAPTER V. CARBON DIOXIDE AND VITAL PROCESSES 136 

Stimulating Plant Growth with Carbon Dioxide, 136. The Indirect Fertili- 
zation of Plants with Carbon Dioxide, 138. The Physiological Action of 
Carbon Dioxide on Animals, 139. Respiratory Stimulant, 139. Therapeutic 
Uses of Carbon Dioxide Gas, 140. The Use of Solid Carbon Dioxide as an 
Escharotic, 141. Carbonated Baths, 142. Carbon Dioxide as an Insecti- 
cide, 144. 

CHAPTER VI. COMMERCIAL MANUFACTURE OF LIQUID CAKIION DIOXIDE . . . 146 
The Furnace, 146, Fuel, 147. Chemistry of Combustion, 148. Scrubbers, 
150. Absorption, 151. Absorption in Water, 151. Absorption in Triethanol- 
aminc Solution, 152. Absorption in Solutions of Alkali Carbonates, 153. 
Equilibrium Relations in Absorption Systems, 154. Rate of Absorption, 157. 
Absorption Mechanism, 157. Experimental Verification, 159. Other Fac- 
tors Affecting the Rate or Degree of Absorption, 161. The Coke Tower, 
164. Other Types f Absorbers, 165. The Operation of a Coke Tower, 106. 
Lye Roiling, 167. Theory of Desorption or Lye Boiling, 170. Condensers, 
171. Gasometer, 172. Purification 172. Liquefaction of Carbon Dioxide, 
175. Oil Removal, 176. Liqukl Carbon Dioxide Condensers, 177., Carbon 
Dioxide from Dolomite, 181. The Process of Fermentation, 183. Purifica- 
tion of Fermentation Carbon Dioxide, 184. 

CHAPTER VII. MANUFACTURE AND DISTRIBUTION OF SOLID CARBON DIOXIDE . . 193 
The Simple Cycle, 196. Precooling Cycle, 198. Bleeder Cycle, f^8. Blecder- 
Precooling Cycle, 199. Pressure Snow-Making Cycle, 199. Binary Cycle, 
201. Removal of Permanent Gases, 204. Removal of Water, 204. The 
Snow Tank 207. Horizontal Presses, 209. Vertical Presses, 212. The 
Carba Process, 213. The Linde-Siirth Process, 218. The Agefko Process, 
218. The Esslingcn Apparatus, 219. The Pegna Apparatus, 219. The 
Maiuri Process, 220. Car Transportation, 222. Truck Transportation, 222. 
Transportation Losses, 222. Economic Problems, 225. Trade Problems, 
226. Engineering Problems, 226. Present Storage Structures, 227. 

CHAPTER VIII. USES OF COMMERCIAL CARBON DIOXIDE 230 

Refrigeration, 230. Cooling and Freezing Uses, 240. Producing Liquid 
Carbon Dioxide, 246. Solid Carbon Dioxide for Rain Making, 247. In 
Mechanical Refrigeration, 248. The Carclox Blasting Device, 248. Liquid 
Carbon Dioxide as a Power Producer, 252. Carbonating Beverages, 254. 
Fire Extinguishing, 254. Preservation of Foods and Flowers, 260. Uses in 
the Canning Industry, 264. Uses in the Chemical Industry, 264. Carbona- 
tion of Water Supplies, 266. Removal of Scale with Carbon Dioxide, 207. 
Carbon Dioxide in the Rubber Industry, 267. Hardening of Cement Prod- 
ucts, 268. Drying and Testing Cables, 2(>8. Chemical Control, 268. 

APPENDIX 271 

INDEXES 285 



Chapter I 
The Early History of Carbon Dioxide 

The intimate relation between carbon dioxide and living things on the 
earth would lead one to expect its history to start with the history of man. 
There is hardly any doubt that the primitive people were aware of the 
presence of this gas, but instead of a material substance they considered it 
to be an evil spirit or demon having the power to slay without leaving any 
evidence of violence on its victim. In the first century of our era, Pliny 1 
mentioned the exhalation of lethal vapor spiritus Icthalcs from certain 
caverns, especially the dog grotto near Naples. 

The actual ^recorded history of this substance, however, starts with the 
writings of J. B. van Helmont (1577-1644). These papers, assembled by 
his son after van Ilclmont's death, were published under the title of Ortus 
mcdicinac. This work makes it clear that van Helmont recognized carbon 
dioxide as a gas, distinct from other gaseous substances, and that he was 
able to study many of its properties. 

Van Helmont discovered that the burning of charcoal produced, besides 
an ash, a substance which he called spiritus sylvestrc , and furthermore, that 
this spiritus sylvestrc is identical with the gns given off during the process 
of fermentation. Other names applied to this substance by van Helmont 
were ya<s carbonnni, gas viuorum, gas uvarum, gas uiusti, etc. In addition 
to these two sources of carbon dioxide, van Helmont discovered four others : 
one from the action of acids on carbonates, (he used vinegar and crabs 
stones); a second from caves, cellars, and mines; a third from mineral 
waters, especially those from Spa, and the fourth, a product of gastric 
fermentation in the intestines. Van Helmont was unable to collect and 
preserve this gas and even declared that it could not be held in any vessel. 
Nevertheless, this early investigator was the first to note the disappearance 
of air when a candle was burned in a jar, inverted over water, and his 
conclusions were, that he was able to produce a void in nature which filled 
immediately with the material substance, water. 

Soon after the time of van Helmont, Fr. Hoffman 2 carried on an 
investigation with the gas escaping from certain effervescing mineral 
waters which he named spiritus mmeralis, although he also referred to it as 
spiritus sulphurus, spiritus aethcrcus, and spiritus elasticus. He observed 
that water charged with carbon dioxide had the power of reddening certain 
blue vegetable coloring matters which he placed in it, and from this he 

1 Pliny, Historiae naturalis. 2, 95 (A. D. 77). 

8 Huffman, "De methode examinandi aquas salubres," Lugduni Batavorum, (1708). 



12 CARBON DIOXIDE 

concluded that the gas caused the water to have weak acidic properties. 
However, L. Lihavius, 3 in 1597, had also noticed the acid character of 
charged water, and attributed it to the presence of imponderable spiritus of 
great volatility. 

Next HaK>s, 4 in the year 1724, carried on a large number of experiments 
on plant transpiration and the distillation products of vegetable matter. 
While Hales added nothing new regarding carbon dioxide, he produced 
the gas and handled it much as we do today. His apparatus for collecting 
gases was his best contribution to the s* *cnce and with slight modifications, 
it is still used, even by those beginning the study of the subject. 

Fr. Venel, 5 Professor of Chemistry at Montpcllier, in 1750, presented to 
the Academy of Sciences two memoirs, the object of which was to prove 
that Seltz water and other acidulous waters owe their pungent taste, as well 
as the escaping gas bubbles to a quality of air, dissolved in them. Venel, 
however, confused this air or gas with ordinary atmospheric air, and his 
writings added nothing to the existing knowledge of the subject. 

About 1757, Joseph Black 6 found that carbon dioxide was a constituent 
of the carbonates or mild alkalies, being combined in them in the fixed or 
solid state; and for that reason he "called it fi.vcd air. Black's skillful 
experimentation proved much which at that time lacked experimental veri- 
fication. He confirmed the ideas of van Hclmont regarding combustion of 
carbonaceous matter and showed that respiration was a process that 
removed part of ordinary atmospheric air and transformed it into fixed 
air. Black discovered the deadly effect that this gas had on animal life 
and he performed many experiments with it on birds and small animals. 

McBride, 7 about 1764, also investigated the formation of fixed air during 
the process of fermentation and putrefaction, and made certain valuable 
observations on its presence in the blood and in the atmosphere. 

Two years later, Cavendish 8 published certain observations which he had 
made on fixed air, especially the fact that fixed air precipitated calcium car- 
bonate from a solution of calcium hydroxide and then on the continued 
addition of the fixed air the precipitate went back into solution. 

While Joseph Priestley's fame is due largely to his discovery of oxygen, 
he really added considerable valuable information to the knowledge of 
carbon dioxide. The presence of a brewery near Priestley's home, stimu- 
lated him to study the gaseous product of the fermentation vats. While 
attempting to mak?, artificially, a water similar to the famous Pyrmont 
product, he found that pressure favored the solution of carbon dioxide in 
water and for this discovery he may be considered the inventor of artifically 

* Libavius, "De judico aquarum mineralium," Francofurti, (1597). 

Hales, "Vegetable Staticks," London, (1727). 

B Venel, Mtm. Acad., 53, 80, 337 (1750). 

9 Black, "Experiments upon magnesia alba, quicklime, and other alcaline substances," Edin- 
burgh, (1777); Alembic Club Reprints, 1 (1893). 

7 McBride, D., "Experimental Essays on the Fermentation of Alimentary Substances and on 
the Nature and Properties of Fixed Air," London, (1764). 

Cavendish, H., Phil. Trans., 56, 141 (1766). 



THE EARLY HISTORY OF CARBON DIOXIDE 13 

carbonated water. Priestly also found that plants were able to live in this 
fixed air whereas animals perished, and further that plants gave to the 
fixed air, properties of common air under the influence of light, but that 
this action ceased at night. 

Regarding the influence of living plants and living animals on the 
composition of the atmosphere, Priestley, from a series of experiments, 
drew conclusions which have withstood the test of time. These ideas are 
even more remarkable when one considers the fact that oxygen, at that 
time, had not been discovered and rather vague ideas prevailed regarding 
nitrogen. Priestley's conclusions can best be given in his own words: 9 

"These proofs of a partial restoration of air by plants in a state 
of vegetation, though in a confined and unnatural situation, cannot 
but render it highly probable, that the injury which is continually 
clone to the atmosphere by the respiration of such a number of 
animals, and the putrefaction of such masses of both vegetable and 
animal matter, is, in part at least, repaired by the vegetable creation, 
and, notwithstanding the prodigious mass of air, that is corrupted 
daily by the'above mentioned causes, yet, if we consider the immense 
profusion of vegetables upon the face of the earth, growing in places 
suited to their nature, and consequently, at full liberty to exert all 
their powers, both inhaling and exhaling, it can hardly be thought, 
but that it may be sufficient counterbalance to it, and, that the remedy 
is adequate to the evil." 

Shortly after the publication of this long dissertation by Priestley, con- 
cerning tlie properties of this gas, an exhaustive work on the history and 
nature of carbon dioxide came out under the authorship of Tobern Berg- 
man, 10 who about 1770 made an exhaustive study of the properties of this 
clastic fluid. Bergman found that water dissolves nearly its own volume 
of fixed air at 10 C. and that the solubility of the gas decreases as the 
temperature increases, lie carefully determined the density of a saturated 
solution of carbon dioxide in distilled water, and found it to be 1.015 at a 
temperature of 2 C. lie demonstrated again by the taste and action on 
litmus that this solution was a weak acid and he proceeded to produce 
water artifically, which imitated that of Seltz, Spa and Pyrmont. He used 
this artificial mineral water for several years and claimed very pleasing 
results. Because of the acid nature of its water solutions Bergman called 
carbon dioxide, acid of air. Some of Bergman's quantitative work on com- 
pounds containing carbon dioxide was of a degree of accuracy that might 
l>e considered good today. He determined the composition of various 
carbonates such as barium, calcium and magnesium and noted that the 
last two were soluble in water solutions of acid of air. 

Bergman was the first to formulate a rational opinion on the composition 
of the atmosphere. He considered it as consisting of three elastic fluids; 

"Priestley, J., Phil. Trans., 62, 127-264 (1772). 

10 Bergman, T. f Opusc., T., 1, "De acido aereo." (1774). 



14 CARBON DIOXIDE 

first, acid of air, which exists in very small amounts; second, what he 
called vitiated air, which served neither for combustion nor for the respira- 
tion of animals ; and third, an air absolutely necessary for fire and animal 
life, that makes up about a quarter of the atmosphere and which he regarded 
as pure air. The density of carbon dioxide, Bergman found, was greater 
than ordinary air, and this explained the phenomenon of asphyxia that 
takes place near the ground, in many places where the gas exists in 
abundance. He cites for example, the fountain in Pyrmont, opened in 
1717, where the geese, having very long necks, were able to swim without 
inconvenience ; the sources of Schwalback and the dog grotto near Naples. 
Bergman's experiments with animals in an atmosphere of carbon dioxide 
were very remarkable. The exactness of his observations, his skill as an 
experimenter and the care with which he examined the animals after death, 
threw much light on the physiological action of carbon dioxide. His experi- 
ments showed that carbon dioxide kills, not only by depriving the victim 
of respirable air, but in exercising a harmful effect on the organism, 
particularly on the blood and the circulatory system. 

Lavoisier 11 proved the composition of fixed air by sho\ying that it was 
produced when carbon was heated in oxygen. He then renamed it acide 
carboniquc a term which, with its English equivalent, carbonic acid, has 
come down to the present time. However, the term carbon dioxide is more 
generally used now for the gas and carbonic acid for its water solution. 
I^avoisier and Laplace 12 found that acide carbonique was composed of 
23.5 to 28.9 parts of carbon with 71.1 to 76.5 parts of oxygen. Lavoisier 
produced this compound by the combustion of the diamond in oxygen. 

While most of the determinations of the compositions of carbon dioxide 
up to this time, were made by the method of synthesis, Smithson Tennant, 
in 1797, determined its composition by an analytical method. He heated 
a small piece of phosphorus with powdered calcium carbonate in a glass 
tube. The phosphorus changed to an oxide at the expense of the oxygen 
of the carbon dioxide, and the liberated carbon was deposited in the tube 
in the form of a black powder. 13 

The Industrial Development of Carbon Dioxide. The industrial 
development of carbon dioxide may be considered to start with the purely 
scientific experiments of Faraday on the liquefaction of gases. It is true 
that much interest was shown before this time in the preparation of arti- 
ficially carbonated mineral water, 14 which was considered especially valu- 
able as a medicine, yet the industry as it is today could not exist without 
the process of liquefaction. 

Faraday's 15 experiments with bent glass tubes, in which he liquefied 
various gases, one of which was carbon dioxide, are well known even to 

11 Lavoisier, A. L. Opuscules physiques et chimiques, Paris, (1774) ; Mem. Acad. t 564, 591 (1772) ; 
520 (1775); 185, 363 (1777); 448 (1781); 593 (1784). 

"Lavoisier, A. L., and Laplace, P. S., Mem. Acad., 359 (1780); 387 (1784). 
18 Tennant, Smithson, Phil. Trans., (1791). 
"Nooth, Phil. Trans., 65, 59-66 (1774). 
Faraday, M., Phil. Trans., 193 (1823). 



THE EARLY HISTORY OF CARBON DIOXIDE 15 

beginners in the science. It is, perhaps well, however, to emphasize at this 
point the important consequences of his work and how it affected the 
future of the industry. 

The idea of making liquids from gases had an immediate appeal to a 
large number of investigators who proceeded to study various gases from 
many different points of view. Thilorier 10 repeated Faraday's liquefaction 
experiments on a much larger scale, using a cast-iron retort instead of a 
glass tube for the gas generator. Two of these retorts were connected 
together, one serving for the generator, in which sodium bicarbonate was 
treated with sulfuric acid, and the other acting as a receiver and condenser 
for the gas as it came over under very high pressure from the generator. 
While Thilorier was able to produce considerable liquid by this method, 
his apparatus was quite tmsuitecl to withstand the terrific strain imposed 
on it and eventually it exploded. This explosion took place before 
a class at the Ecole de Pharmacie, Paris, and the fragments of the shattered 
cast-iron receiver cut off both legs of the unfortunate operator, M. Hervy 17 
who, at the time, was swinging the generator to and fro for the purpose of 
mixing the charge. From this injury, Hervy died a short time after. 
Thilorier, however, made many valuable observations on the dilation, vapor 
pressure, density and heat change of this liquid during vaporization. While 
vaporizing the liquid, Thilorier 18 produced solid carbon dioxide for the 
first time. He obtained this as a white flocculent mass, resembling snow, 
which, like snow, was readily compressed. Thilorier gives the following 
description of this interesting substance: "When the solid is exposed to 
the air it disappears insensibly by slow evaporation, without melting. A 
fragment of the solid, slightly touched by the finger, glides rapidly over a 
polished surface, as if it were sustained by the gaseous atmosphere with 
which it is constantly surrounded. The vaporization of solid carbon 
dioxide is complete; it leaves but rarely a slight humidity which may be 
attributed to the action of air on a cold body, the temperature of which 
is far below that of freezing mercury. The snow can be handled without 
harm, but when pressed on the skin for a few seconds or more, it produces 
blisters." 

Mareska and Donny 10 improved Thilorier's liquefying apparatus and 
made it much safer by constructing it of lead and surrounding the lead 
retorts with copper jackets reinforced with wrought-iron bands. Two of 
these cylinders were connected together with a small flexible copper tube in 
order that the one serving as a generator could be rocked backwards and 
forwards for agitating the mixture. The generating cylinder was charged 
with sodium bicarbonate while the sulfuric acid, necessary for the reaction, 
was inclosed in a small internal cylinder. Mixing was accomplished by 
tilting the generator until the acid flowed into the bicarbonate solution. 

Thilorier, M., Ann. chim. phys., (2) 60, 427 (1835). 
"Anon., /. Chem. Mcd., 17, 61. 

"Thilorier, M., Ann. chim. phys., (2) 60, 432 (1835). 

Mareska, T. and Donny. F., Mfm. Couron. Bruxellcs, 18, 1 (1845); /. prakt. Chem. t (1) 
35, 226 (1845); Contpt. rend., 26, 817 (1845). 



16 CARBON DIOXIDE 

During the year 1845, several important steps were taken in the direc- 
tion of the commercial utilization of carbon dioxide. Addams 20 had pre- 
viously been able to produce liquid carbon dioxide with a hydraulic pump. 
This apparatus now served Faraday 21 for the preparation of large amounts 
of the liquid from which he was able to make considerable solid carbon 
dioxide. Faraday mixed this solid carbon dioxide with ether and by means 
of a vacuum pump was able to decrease the gas pressure over the mixture, 
reducing the temperature thereby to a value somewhat below 100 C. 
This freezing mixture was used in the famous research which Faraday pub- 
lished at this time on the liquefaction of gases. Then Joliann Natterer 22 
working under the direction of Professor Pleischl in Vienna, developed a 
mechanical compressor with which he was able to produce liquid carbon 
dioxide. His machine was of the single-acting compression type and 
several hours of hard work were required to produce a pound of the liquid. 
Nevertheless, in spite of its crudeness, it was the forerunner of the modern 
multi-stage compressors. 

In 1873, the United States Navy Department purchased a "Lay Tor- 
pedo" with the Lay apparatus for producing the liquid carbon dioxide 
necessary for propelling and steering it. Walter Hill, 23 forking at the 
Naval Station at Newport, R. I., was assigned the task of producing the 
required carbon dioxide with this apparatus and testing the torpedo. The 
Lay process was similar to that already used by previous investigators, 
in which sodium bicarbonate was treated with sulfuric acid and Hill soon 
found that it was quite impractical for producing the large quantity of liquid 
needed for the operation of the torpedo. Seven hundred pounds of this 
liquefied gas were necessary for filling the torpedo, and to accomplish the 
work necessary for compressing this vast amount of gas, Hill obtained 
a compressor from the Burleigh Rock Drill Company, Fitchburg, Massa- 
chusetts. In 1874, in less than two working days, 315 Ibs. of this liquid 
had been made, using marble clust and sulfuric acid for producing the gas, 
and the mechanical compressor for reducing it to a liquid. A few weeks 
later, 380 pounds more were compressed, tlyjs completing the charge neces- 
sary for the torpedo. Several hours after this work was finished, one of 
the flasks containing the liquid carbon dioxide burst, while lying in a 
shed used for housing the torpedo. The other flask was condemned as 
unsafe and immediately destroyed. New flasks were made, but no more 
liquid was produced until 1875. Hill, at this time, was able to compress 
carbon dioxide at a rate of 46 Ibs. per hour at a cost of 24.9 cents per pound 
for the first, and not over 21 cents per pound for the second lot. He esti- 
mated that the liquid could be made for less than 15 cents per pound, 
with an apparatus similar to the one he used. 

* Addams, R., Report of Brit. Assoc., 70, (1838). 

81 Faraday, M., Phil. Trans., 155 (1845). 

M Natterer, Johann, /. prakt. Chem., (1) 31, 375 (1844). 

"Hill, Walter, "Liquid Carbonic Acid,'* Newport, (1875). 



THE EARLY HISTORY OF CARBON DIOXIDE 17 

In the year 1877, Dr.Hendryk Beins, in Groningen took out a patent on 
the production of liquid carbon dioxide by heating sodium bicarbonate. 
He was interested in the liquid, which he called "carboleum," as a motive 
power. In his discussion of the advantages of "carboleum" over other 
forms of power, Beins said "It can be used: (1) for locomotives; (2) for 
steam boats; (3) for small factories such as sewing machines, pumps, and 
lathes; (4) in fire extinguishers as a gas or 'solution; (S) as a source of 
power for electrical machines for street lighting, lighthouses, telegraphs, 
etc.; (6) as a 100 times cheaper projectile propeller than powder; (7) in 
the accomplishment of scientific undersea navigation for war purposes and 
perhaps for operating air ships; (8) for ice machines; (9) for mineral 
water as well as a source of pure carbon dioxide." 

Beins' experiments with carbon dioxide as a propelling medium for sub- 
marines, interested the Dutch Navy to such an extent that the Minister 
of Marine, after an intelligent official test, which found it feasible, furnished 
financial assistance for carrying out the project. 

An important event took place on August 28, 1879, when carbon diox- 
ide was put to practical use on rather a large scale. On this day, Dr. W. 
Raydt, in Germany, attached a deflated balloon to an anchor on the bottom 
of the sea, in Kiel harbor, inflated it with carbon dioxide gas, and in just 
eight minutes had raised the anchor to the surface of the ocean, a distance 
of 10 meters. Then Raydt tried to raise some sunken steamers, but finally 
turned to the use of carbon dioxide for raising beer, and for making soda 
water. The anchor episode, while of no great importance in itself, turned 
the eyes of many inventors and scientists to the compound responsible for 
it, and from this time on, carbon dioxide received a great deal of attention 
as a potential article of commerce. Five years later, Raydt had established 
a factory for the production of liquid carbon dioxide, and part of the 
product from that factory was used by the Krupp Iron Works for com- 
pressing liquid iron into the molds. Raydt's factory became of great eco- 
nomic importance in later years, and this fact, more than his experiments 
with the anchor, is responsible for the statement, often made, that he is the 
father of the liquid carbon dioxide industry. 

In 1882, Raydt 24 constructed an apparatus for carbonating water under 
pressure, for use as a fire extinguisher. This apparatus was tested at the 
Krupp Steel Works and by the Fire Department in Berlin, and in both 
cases was found to be superior to any other type of extinguisher at that 
time in existence. The fire director and chief of the department of the 
Krupps in Essen, writes as follows, regarding the Raydt system: "The 
principal advantage of the Raydt method lies in the fact, that one can, 
immediately, on the breaking out of a fire, without any preparation produce 
any desired pressure and form a very effective solution of carbon dioxide, 
which can be handled by a very much smaller service crew. The author 
has convinced us that very large theater, factory, and ship fires can be 

"Raydt, W., Polyt. Notisbl., 37, 196 (1882). 



18 CARBON DIOXIDE 

avoided by the use of the Raydt solution apparatus when taken at the right 
time." Then followed Raydt's patent on the ice and refrigerating machine 
(D. R. P. No. 33168) in the year 1885. Other patents followed in rapid 
succession, until Raydt became by far the most important figure in the 
industry. 

At this time, the liquid carbon dioxide industry depended upon two fac- 
tors for development, first the development of compressors capable of com- 
pressing large quantities of the gas, and second the development of a market 
sufficient to absorb the product. Plenty of carbon dioxide came from the 
earth in many places, especially in Germany, so the manufacture of the 
gaseous compound was of small importance. However, to avoid transpor- 
tation of the heavy cylinders and their contents, the need for other methods 
of manufacturing the gas was sqon evident and in 1889 the Kolensaure- 
Werke in Erkner near Berlin started making carbon dioxide by the coke 
process. 

The names of many men were closely associated with the industry at 
this time. The Beins brothers, H. Beins and his brothel* T. F. Beins, had 
devised an apparatus for producing mineral water and had established a 
company for manufacturing it. Dr. Hugo Kunheim was vey active both 
as a manufacturer and as an investigator. Hugo Baum was the first to use 
natural carbon dioxide from a well in Burgbrohl in the Kifel. C. G. Rom- 
menholler became a leading figure as a manufacturer of carbon dioxide and 
was connected with many enterprises using both natural and coke process 
carbon dioxide. 



Chapter II 
Carbon Dioxide in Nature 

Notwithstanding the very low concentrations of carbon dioxide in the 
earth's atmosphere, its importance to plants and animals as a part of the 
life process cannot be over-emphasized. Being" a food for the vegetable 
kingdom and a waste produce from animal life, it is, to a certain extent, 
a connecting link, which by its regulatory powers, controls the extent of 
life in each. The situation, however, is very complex. The information 
at present available is both scant and to a certain extent inaccurate. It is, 
therefore, not to be expected that a complete and well founded exposition 
of nature's modus operandi, with respect to carbon dioxide, cadfjfethis 
time be given. . - l^^B 

Occurrence in the Atmosphere. The exact concentration otcarbon 
dioxide in air over wooded areas, desert land, in the atmosphere near the 
north and south poles, over the seas, lakes, etc., becomes of great importance 
to those working in the field of photosynthesis and perhaps only to a lesser 
extent in many other fields. 

In 1769, H. B. de Saussure 1 made an investigation of the carbon dioxide 
content of the air in the mountains and on the plains of Switzerland. Later, 
his son, N. T. de Saussure 2 continued this investigation and arrived at 
some very interesting conclusions, regarding the variability in amounts 
of this gas in the atmosphere and some of the factors influencing its con- 
centration. His most remarkable observation concerned the difference in 
concentration of carbon dioxide during day and night. His values obtained 
at night were somewhat higher than those obtained during the day. 

These early determinations are more valuable for their historic signifi- 
cance than for their scientific utility. A few other analyses collected by 
Mellor 3 are also interesting as they were made on air from many different 
part of the earth. These values, shown in Table 1, vary between rather 
wide limits, i. e. from 2.43 to 3.90 volumes per 10,000 volumes of air. This 
deviation is somewhat greater than one might expect and is, perhaps, due 
to lack of refinement in the technique of sampling and analyzing, rather 
than to actual variation in the carbon dioxide concentration. 

Certain disturbing factors may greatly affect the carbon dioxide concen- 
tration of the atmosphere at any one point and unless these are guarded 

*de Saussurc, II. B. f "Voyages dans les Alpes," Gcnere, 4, 202 C1796). 
'de Saussure, N. T., Ann. chim. phys., (2) 38, 411 (1828); (2) 44, 5, (1830). 
3 Mellor, J. W. t "A Comprehensive Treatise on Inorganic and Theoretical Chemistry," 6, page 3. 
Longmans, Green and Co. (London.) (1925). 

19 



20 CARBON DIOXIDE 

TABLE 1. Concentrations of Carbon Dioxide at Various Points on the Earth. 
Source of sample IftOW^S? oHir Observer 



Paris ..................... 3.027 J. A. Reiset 

Dieppe ................... 2.942 J. A. Reiset 

Bloomington, Ind .......... 2.816 T. C. van Niiys and 

B. F. Adams 
Country of Belgium ...... 2.944 A. Petermann and 

J. Graftiau 
Gembloux ................. 3.700 A. Pctermann and 



T. Graftiau 
W. C. 



Sheffield 3.90 W. C. Williams 

1.5 miles west of Sheffield. . . 3.27 W. C. Williams 

Mont Blanc, 1080 m 2.62 M. de Thierry 

Mont Blanc, 3050 m 2.69 M. de Thierry 

Belfast 2.91 E. A. Letts and 

R. F. Blake 
Kew (max. and min.) 2.43 to 3.60 H. T. Brown and 

F. Escombe 

REFERENCES 
Reiset, J. A., loc. cit. 

Petermann, A. and Graftiau, J., M6m. Acad. Bclq., 47, 2 (1892). 
Williams, W. C., Clicm. News, 76, 209 (1897); Bcr., 30, 1450 (1897). 
de Thierry, M., Compt. rend., 129, 315 (1899). 

Letts, E. A. and Blake, R. F., Proc. Roy. Soc. (Dublin) (2) 9, 107 (1900). 
Brown, H. T. and Escombe, F., Proc. Roy. Soc. (London), 76, B 118 (1905). 

against the determinations may have but little value. Thus, Reiset 4 made 
several analyses, 8 kilometers from the city of Dieppe and obtained an 
average value of 2.917 vols. of carbon dioxide per 10,000 vols. of air. 
When, however, a drove of sheep entered the region of sampling, the car- 
bon dioxide concentration rose to 3.178 volumes. Samples taken near the 
ground are affected by the character of the soil, the presence of decaying 
organic material, and the presence of water. The effect of proximity of 
human habitation to the source of sampling is shown in the results of 
Haehnel 5 who made a series of determinations of the carbon dioxide con- 
centration in the air of Berlin. This investigation was made in an attempt 
to determine the cause of weathering of stone and metal structures. His 
results showed a value of 24 parts of carbon dioxide per 10,000 parts of 
air which is so far above the amount usually found, even in cities, one is 
led to suspect that the samples did not represent true averages. Florentine 6 
collected 27 samples at various seasons of the year in the streets of Paris 
and found that the carbon dioxide concentration ranged from 3.4 to 6.2 
vols. per 10,000 vols. of air. Confirmation of these results were made by 
Cambier and Macy 7 who nearly a year later obtained values from 3.4 to 6 
parts carbon dioxide per 10,000 parts of air. The samples were taken two 
meters above the ground in the streets of Paris. 

4 Reiset, J. A., Comfit, rend., 88, 1007 (1879). 

Haehnel, O., Z. angew. Chcm., 35, 618-20 (1922). 

Florentine, 1)., Compt. rend., 185, 1538-41 (1927). 

'Cambier, R., and Macy, F., Compt. rend., 186, 918-21 (1928). 



CARBON DIOXIDE IN NATURE 21 

One of the most valuable investigations of the carbon dioxide tension of 
the air was made by Benedict 8 on 212 samples, taken under conditions 
well removed from disturbing influences and over a period extending from 
April 1911 to January 1912. His samples, from which he obtained an 
average of 3.1 vols. per 10,000 vols. of air, were collected under various 
conditions of weather, pressure of the atmosphere, temperature, humidity 
and wind velocity, furthermore, the experiments were made before, during 
and after the vegetation season. The agreement between the individual 
determinations was remarkable and essentially the same results were 
obtained from air taken from the top of Pike's Peak in Colorado and sam- 
ples taken over the ocean. The air of crowded city streets showed much 
higher concentrations and in subway stations in New York and Boston, 
he found about twice the normal amount. 

A series of determinations made by Lundegardh on the island of 
Hollands Vadero, 3.2 kilometers from the mainland of Sweden, show only 
a very slight variation over a series of years when the same method of 
analysis was used. The results he obtained were : 



3295 vols. per 10,000 vols. of air. 

1921 .............. 3.031 vols. per 10,000 vols. of air. 

1922 .............. 2.843 vols. per 10,000 vols. of air. 

1923 .............. 3.000 vols. per 10,000 vols. of air. 

Moss 10 found the air over the Arctic to be richer in carbon dioxide than 
that over England. Krogh 11 found the concentration of this gas in the air 
over Greenland to vary between 2.5 and 7 vols. per 10,000 vols. of air. 
Schulz 12 reports values over the North Sea and Baltic ranging from 2.7 
to 3.2 with a mean value of 2.93. Miintz and Lainc 13 determined the car- 
bon dioxide content of air in the Antractic regions. Between 64 49' and 
70 5' the average carbon dioxide content of the air is 2.0524; at 69 3(X 
only 1.447 and at 70 5', 1.702 parts per 10,000 parts of air. The explana- 
tion of this decrease depends upon the fact that the dissociation pressure 
of bicarbonates decreases with a decrease in temperature and is extremely 
small at temperatures of and below. Ix?gendrc 14 analyzed the sea air 
off the coast of France and obtained a value of 3.35 vols. of carbon dioxide 
per 10,000 vols. of air. 

All of these determinations, with the wide variation in results, leave 
one rather confused as to the most probable concentration of carbon dioxide 
in the atmosphere. Reinau lr> attaches considerable importance to these 
variations and has attempted to account for them by means of an elaborate 

8 Benedict, F. G., "The Composition of the Atmosphere with Special Refciencc to its Oxygen 
Content," Carncuie Ittst., Washington, Pub. 166, (1912). 

9 Lundcgardh, II., "Der Kreislauf der Kohlensaure in dcr Natur," Jena p. 9 (1924). 

10 Moss, E. L., Proc. Roy. Soc. (Dublin), (2) 2, 34 (1878). 

"KroRh, A., Mcdd. Gronland, 26, 409 (1904); Compt. rend., 139, 896 (1904). 

"Schulz, Arch, dcutsch. Sccwarte, 40, 16 (1922); 41, 6 (1923). 

18 Miintz, A., and Lainc, E., Compt. rend., 153, 1116-9 (1911). 

"Legendre, R., Compt. rend., 143, 526 (1906). 

"Reinau, E., "Kohlensaure and Pflanzen." Halle (1920). 



22 CARBON DIOXIDE 

theory. However, it is very likely, as Spoehr 16 points out that these varia- 
tions are due to errors inherent in the methods used for analysis and it is 
rather risky to attach too much importance to them. For calculations requir- 
ing a knowledge of the concentration of atmospheric carbon dioxide, the 
value ordinarily used is 3 vols. per 10,000 vols. of air or 0.03 per cent by 
volume. 

From the analytical data already obtained various attempts have been 
made to estimate the total carbon dioxide in the atmosphere. Clark 17 cal- 
culated that the atmosphere of the earth contains 2.2 X 10 12 tons of this gas 
while Krogh gives a value of 2.4 X 10 12 tons and van Hise 18 and Dittmar 19 
obtain similar estimates. Chamberlin, 20 however, gives a somewhat higher 
value. The amount taken for calculations involving this factor, is usually 
about 2.2 xlO 12 tons or 2.0 XlO 15 kilograms. 

Occurrence in the Hydrosphere. By the hydrosphere is meant that 
layer of liquid water which covers such a large part of the earth's surface. 
In this liquid, carbon dioxide is soluble and, in addition, it is capable of 
acting as a medium in which many reactions involving carbon dioxide may 
take place. That the sea acts as a tremendous reservoir for carbon dioxide 
cannot be doubted. From this reservoir, carbon dioxide can*be liberated to 
the atmosphere if its partial pressure in the air falls below that exerted by 
the gas in solution. Or, on the other hand, it can remove the gas from the 
atmosphere when an increased carbon dioxide tension prevails. The solu- 
tion of carbon dioxide in ocean waters is not a simple case of gas dissolved 
in a liquid but rather a gas dissolved in a solution of many substances, some 
of which act chemically with the carbon dioxide. Not only the inorganic 
solutes present in ocean water affect the concentration of the gas, but 
many plants and animals live in these waters and their relation to the carbon 
dioxide balance is very much the same as that of their counterparts on 
the land. 

From available data, it seems that there is even a wider variation in the 
concentration of carbon dioxide in the sea than has ever been observed in 
the atmosphere. Roughly, however, this concentration is about 5 vols. 
of the gas per 10,000 vols. of sea water. It has been estimated that the 
sea contains from 20 to 30 times the carbon dioxide existing in the atmos- 
phere, thus making a total quantity as great as 6.6 XlO 13 tons. 

The carbon dioxide in the sea may exist in the form of carbonates, bicar- 
bonates, carbonic acid and its ions, and the dissolved gas. That part of 
this compound existing as a carbonate, may be considered as more or less 
fixed. It is no longer available as a gas unless its compounds undergo 
some radical treatment by which the carbon dioxide is again liberated. 
However, half of that in the form of bicarbonates is rather loosely com- 

Spoehr, II. A., "Photosynthesis," page 38, The Chemical Catalog Co., Inc., New York (1926). 

"Clark, F. W., Data of Geo-Chemistry, Washington, (1920). 

"van Hise, C. R., Man. U. S. Geol. Survey, 47, 964 (1904). 

"Dittmar, W., "Report on the Composition of Ocean Water," London, (1883). 

"Chamberlin, T. C, Geol., 5, 653 (1897). 



CARBON DIOXIDE IN NATURE 23 

bined and will be given up again as gaseous carbon dioxide with a change 
in temperature or pressure of the gas over the liquid. All of that carbon 
dioxide, in the form of carbonic acid, is easily recovered if the temperature 
of the water increases. Each of these forms and their respective ions are 
related to each other and tend to form an equilibrium in which the carbon 
dioxide of the atmosphere takes part. 

The concentration of carbon dioxide in the sea has been the subject of 
many investigations. Fox 21 found the concentration to vary from 1 to 7 
vols. of carbon dioxide per 10,000 vols. of sea water. The more recent and 
extensive results of Schultz, 22 obtained during a study of the North Sea 
and the Baltic Sea, give a much better idea of this value. Some of the 
results obtained by Schulz arc given in Table 2. 

TABLE 2. Concentration of Carbon Dioxide in the Air f in Fresh Water 
and in Sea Water. 

In the atmosphere 3 vols. per 10,000 vols. of air 

In fresh water, at 5.1 vols. per 10,000 vols. of air 

at 20 2.6 vols. per 10,000 vols. of air 

In sea wfttcr, at (3.5% NaCl) 4.4 vols. per 10,000 vols. of air 

at 20 2.3 vols. per 10,000 vols. of air 

Much evidence 23 points to the fact that the carbon dioxide of the sea is 
mostly in the form of bicarbonates or its ions and that this compound is in 
equilibrium with the dissolved carbon dioxide, which in turn, is regulated 
largely by the carbon dioxide tension of the atmosphere. Also, the carbon 
dioxide in sea water is not sufficient to transform all the normal calcium 
carbonate into the form of bicarbonate. According to Dittmar the dis- 
sociation pressure of the bicarbonate in sea water is 0.0005 atmos. at a 
temperature of about 18 to 21 C. and falls off to zero at the temperature 
of freezing water. As the carbon dioxide tension of normal air is about 
.0003 atmos., it follows that the colder parts of the ocean are constantly 
removing carbon dioxide from the atmosphere, while the warmer portions 
are constantly giving it up. 

The question of whether there is ever a complete equilibrium between 
the carbon dioxide of the air and that in the sea, has, at present, no answer. 
Perhaps one can do no better than to consult Spoehr's 24 work on "Photo- 
synthesis" for a more complete and detailed discussion of this subject. 

Occurrence in the Lithosphere. From numerous eruptive vents and 
active volcanoes scattered pretty well over the whole earth, gases are pour- 
ing forth, and have been, since the beginning of time. Carbon dioxide 

Fox, C. J. J., Trans. Faraday Soc., 5, 68 (1909). 

Schultz, B., Naturwiwnschaften, 12, 105-113, 126-133 (1924). 

28 Jacobsen. O., Die Eryrebinisse der UntersuchanRsfahrten Drache, Berlin (1886) ; Licbh's An*., 
17, 1 (1873). Hamber*, A., Svensaka Akad. Handl., 10, 13 (1885V, /. prakt. Chem. t (1) 33, 
433 (1886). Torneo, II., Den Norske Nordhays-Expedition, Chemistry, Christiania. 1. (1880). 
Natterer, F., Monatsh, 14, 675 (1893); 15; 596 (1894); 16, 591 (1895); 20^ 1 (1899). Dittmar, W., 
Challenger Reports. Physics and Chemistry, 1, 212, 221 (1884). Buchanan, J. Y., Proc. Roy. Soc. 
(London), 22, 192, 483 (1874). 

* Spoehr, H. A., "Photosynthesis," pages 40-46, The Chemical Catalog Co., Inc., New York (1926). 



24 CARBON DIOXIDE 

occurs in practically all of these gases, in quantities which may vary from 
very low concentrations to a practically pure compound. All igneous rocks 
contain gases which they give up when strongly heated in a vacuum. 
Analyses have shown that the principal constituents of the gas obtained 
in this manner are : water, carbon dioxide and hydrogen while carbon mon- 
oxide, nitrogen, methane and hydrogen sulfide are subsidiary. Carbonates 
of calcium and magnesium, when subjected to volcanic intrusion, give off 
carbon dioxide because they are dissociated so easily by heat. Bituminous 
shales, when heated give off the products of dry distillation and in the gases 
from such a reaction, carbon dioxide is always present. Also, we have 
what are known as secondary fumaroles, which give off gases produced by 
the surface water acting on the hot detritus. The water is vaporized by the 
heat and the steam reacts chemically with the hot detritus, forming various 
quantities of volcanic gas. Table 3 taken from the extensive data of Allen 25 
shows the analysis of a few typical volcanic gases. 

TABLE $. Showing the Per Cent by Volume of Carbon Dioxide, Nitrogen, and 
O.vyycn in Various Volcanic Gases. 

Source Date CO a * N 2 O 2 

Hawaii, the crater 1912 62.3 13.8 0.0 

Vesuvius, edge of great crater 1865 4.8 75.6 19.6 

Phlegrean Fields, Torre del Greco, Flow of 1694 1869 90.2 6.2 0.08 

Etna, Crater R, fumarole 1865 5.0 77.28 17.27 

Sicily, Salinelle of Paterno Acqua Rossa 1856 97.9 2.1 

Lipari Isles, Vulcano, near the Chemical Works 1856 86.0 14.0 

Santorin, Port of George 1870 98.8 1.8 0.4 

West Indies, Guadeloupe Kumarolc of the North 1904 52.8 36.07 7.5 

Colombia, S. America, Purace Solfatara 1868 98.2 

Iceland, Krisuvik, second fumarole 1846 88.24 0.69 

Katami, Ten Thousand Smokes, Nova Rupta 

Basin 1919 70.4 12.8 1.0 

Canary Islands, Pico de Teyde, South Fumarole 1907 71.1 26.9 

The curious effects produced on plant and animal life by these volcanic 
gases, where they escape from the earth, have been described by several 
writers. A few of these descriptions may be worthy of note here. 

M. Boussingault describes a visit he made to a locality near the volcano 
of Tunguragua in 1851 in this manner: "Our horses soon gave us indica- 
tions that we were approaching it; they refused to obey the spur, and 
threw up their heads in a most disagreeable fashion. The ground was 
strewn with dead birds, among which was a magnificent blackcock, that 
our guides at once picked up. Among the victims were also several reptiles 
and a multitude of butterflies. The sport was good, and the game did 
not seem too high. An old Tndian, Quichua, who accompanied us, declared 
that, to procure a good sleep, there was nothing like making one's bed upon 
the Tunguravillc." 

Near Naples is found a cave which has become famous under the name 
of Grotta del Cane (the cave of the dog) from which a gas issues contain- 

Allen, E. T., J. Franklin Inst., 193, 29-80 (1922). 



CARBON DIOXIDE IN NATURE 25 

ing about 70 per cent carbon dioxide, 24 per cent nitrogen and 6 per cent 
oxygen. Flammarion 20 thus describes this interesting cave: This grotto 
is situated upon the slope of a very fertile hill, opposite, and not far from 
Lake Agnano, The entrance is closed by a gate of which the keeper retains 
the key. The ground in this cavern is very earthy, damp, black, and at 
times heated. It is, as it were, steeped in a whitish mist, in which can be 
distinguished small bubbles. This mist is composed of carbonic acid gas, 
which is colored by a small quantity of aqueous vapor. The stratum of gas 
is from ten to twenty-five inches high. It represents, therefore, an inclined 
plane, the highest part of which corresponds to the deepest portion of the 
grotto, and this is a physical conseqence of the formation of the ground. 
The grotto, being about the same level as the opening leading into it, the 
gas finds its way out at the door, and flows like a rivulet along the hillpath. 
The stream may be traced for a long distance, and a candle dipped into it 
at a distance of more than six feet from the grotto, is extinguished at 
once. A dog dies in the grotto in three minutes, a cat in four, a rabbit in 
seventy-five seconds. A man could not live more than ten minutes if he 
were to lie down upon this fatal ground. It is said that the Emperor 
Tiberius had two slaves chained up here, and that they perished at once; 
and that Peter of Toledo, Viceroy of Naples, shut up in the grotto two men 
condemned to death, whose end was as rapid." 

The Valley of Death in Java, is an old volcanic crater with fissures from 
which escape large quantities of carbon dioxide. At times this gas covers 
the floor of the valley like water and the unwary animal venturing into it, 
increases the number of white skeletons which arc scattered over the ground. 
An excellent description of this valley was given by London. 27 

The Stygian Caves in Yellowstone National Park are interesting, as 
they have concentrations of carbon dioxide, sufficient to make them danger- 
ous to animal life, yet it is said, that bears safely hibernate in them during 
the winter months. A few other caves, also of the same origin, that is, 
fissures of ancient hot springs, have low concentrations of this gas. 

The Laachcr Lake in Germany is the water-filled crater of a prehistoric 
volcano, and near by is a depression filled with carbon dioxide. Birds 
and insects flying in this region are killed by the gas. Many tragedies 
have resulted because of the carbon dioxide collecting in cellars of houses 
in the vicinity of this crater. 

In former times the accidents caused by carbon dioxide in caves, mines, 
and even in wells, gave rise to the most extravagant stories. Such localities 
were said to be haunted by demons, gnomes, or genii, the guardians of 
subterranean treasures, whose glance alone, caused death, as no trace of 
lesion or bruise was to be found on the unfortunate persons so suddenly 
struck down. There is some reason for believing that the convulsions of 
the pythonesses, charged with expounding the decrees of the gods, were 
produced by the priests, with carbon dioxide gas. 

99 Flammation, "The Atmospheie," Harper and Brothers, New York (1873). 
"Loudon, A., Edinburgh Phil. J. (2), 12, 102 (1831). 



26 CARBON DIOXIDE 

Natural waters practically always contain carbon dioxide. These waters 
may be divided into two general classes : first, those waters saturated, or 
nearly so, with carbon dioxide under the partial pressure found in normal 
air, and second, those waters containing carbon dioxide dissolved under 
pressure which effervesce when the pressure is released as the water comes 
to the surface of the earth. In the first class, one may place the surface 
waters of the earth and most wells. In the second class may be included 
those springs and wells, the waters of which have been charged with carbon 
dioxide under pressure by some chemical process in the earth. The acidity 
of these waters, due to the carbon dioxide, increases their dissolving action 
for rock material thus producing the so-called mineral waters. 

Many of our most famous carbonated springs occur in Germany, a 
country exceptionally well favored with numerous sources of carbon dioxide 
in the form of springs and even practically dry gas wells. A few of the 
famous springs of Germany are found at Altwasser, Pyrmont, Reinerz, 
Salzbrunn and Seltzer. France is supplied with a number of carbonated 
springs in the Auvergne and in the midst of the Vivarais while this country 
has many like those located at Saratoga Springs, New York; in the Navajo 
and Ute Springs, Manitou, Colorado; the Napa Soda Springs, California, 
and the Hot Springs in Virginia. Apollinaris water, obtained from a 
spring in the Valley of Aar, near the Rhine, is an example of what is called 
an acid water, while Vichy, another famous spring water, has an alkaline 
reaction. 

One of the most complete and exhaustive works dealing with mineral 
waters is that of Bouquet 28 who wrote a long report on the analysis of the 
mineral waters from many of the sources at Vichy and the vicinity. Seven- 
teen of these sources delivered 610,776 liters of water per day from which 
714 kilograms of carbon dioxide was liberated as a gas, and many times 
that amount was carried away in the form of carbonates and bicarbonates. 

Castellr describes some natural carbon dioxide springs in the territory 
of Montepulciano in the Saint Albino region in Italy. The zone 
covers an area approximately 500 meters square, and is made up of various 
Pliocene rocks. The fissures are filled with slightly opalescent water, 
through which the gas issues, causing the appearance of boiling, though the 
water is only slightly above C. and the carbon dioxide 5 to 10 C. 
Several hundred cubic meters of gas is given off each day having the aver- 
age composition: CO 2 , 95 A per cent: O 2 , 0.33 per cent; N 2 , 3.13 per cent; 
combustible gases 0.14 per cent and H 2 S, a trace. 

The numerous boiling springs found in Yellowstone National Park, 
give off large amounts of gaseous carbon dioxide to the atmosphere. The 
gases escaping from these springs, consists of steam mixed with various 
amounts of gas composed largely of carbon dioxide. One rather interesting 
formation, "The Dragon's Mouth," was investigated by Quinn who found 
the vapors responsible for the spewing of hot water from a small cave, to 

"Bouquet, M. t Ann. chim. phys. (3), 42, 278-363 (1854). 
w Caste11i, G.. Pass. min. met. chcm., 58, 14-5 (1923). 



CARBON DIOXIDE IN NATURE 27 

include besides steam, a gas containing 34 per cent carbon dioxide. This 
value is very likely low as the difficulties connected with taking samples 
made the presence of air in the sample possible. A gas bubbling up through 
the mud only a few paces from this formation consisted of 96.5 per cent 
carbon dioxide. 

Besides springs of carbonated mineral water, carbon dioxide comes to 
the surface of the earth, sometimes under great pressure, with various 
amounts of water. In some cases, the gas is practically dry and pure 
enough to be used directly for commercial purposes. Many of these sources 
were used industrially during the early history of carbon dioxide and inter- 
est in their commercial application seems to be again increasing. 

At Pergine (Tuscany) there is an abundant source of carbon dioxide 
which was at one time used industrially by the firm of Cesare Pegna and 
Sons, of Florence. About 1885, a shaft, 52 meters deep, was sunk at 
Burgbrohl, and also one at Hocnningen on the Rhine. Measurements 
reported by Heusler, 30 indicated a water flow of 430 liters and a carbon 
dioxide flow of 1500 liters per minute or 2160 cubic meters per 24 hours. 
A factory was located at this point for compressing the gas into cylinders 
and some of it-*was also used for making white lead. Forbes 31 describes a 
most interesting spring in Bavaria in this manner: "The brine spring is 
about a mile from Kissingen, Bavaria. It has 3 per cent salt, and rises in 
a bore, 325 Bavarian feet deep, in red sandstone ; but it is understood that 
the water flows at about 200 feet in depth. Its temperature is never less 
than 65, the mean temperature of springs near being only 50 to 52. 
It discharges carbonic acid gas in volumes almost unexampled, keeping the 
water in a state resembling turbulent ebullition. The enormous supply of 
gtis has led to its use in gas baths, for which purpose it is carried off by a 
tube connected with a huge inverted funnel, which rests upon the water. 
It contains scarcely a trace of nitrogen. It is conducted into chambers 
properly prepared, and thence into baths, in which it lies by its weight, and 
is used as water would be. But the most remarkable feature still remains. 
About five or six times a day, the discharge of gas suddenly stops ; in a 
few seconds the surface of the well is calm. The flow of water, amounting 
to 40 cu. ft. per minute, also stops or rather becomes negative, for the 
water recedes in the shaft even when the pumps, commonly used to extract 
the brine, do not work, and the water subsides during 15 to 20 minutes. 
It then flows again, the water appearing first, then suddenly the gas, which 
gradually increases in quantity until after three-quarters of an hour, the 
shaft is full as at first. This discharge has continued with little variation 
since the bore was made in 1882. Within a short distance is a bore 554 
Bavarian feet deep, which exhibits somewhat similar phenomena." 

In 1895, C. G. Rommenholler established a carbon dioxide works in 
Herste near Driburg in Westfalen. This was the largest plant built up to 
that time. The giant well poured forth carbon dioxide at a rate of over 

Heusler, 7. Soc. Chem. Itid., (abst.) 743 (1885). 
Forbes, Am. 7. Sci. and Arts, 35, 293 (1893). 



28 CARBON DIOXIDE 

a ton each hour, 32 enough to supply half of Germany with chemically pure 
gas (according to the analysis of Konig it was 99.84 per cent pure). On 
calm days this giant fountain sent its white froth nearly 200 feet high, from 
which height it fell down in a fine glistening spray. Stones, the size of the 
fist, when thrown into the fountain, were hurled by the force of the stream 
high into the air, with a whistling sound similar to that of a meteor falling 
to the earth. This well was controlled only after considerable difficulty. 

The many natural sources of carbon dioxide in the United States have 
not proved popular as commercial sources of the gas. The Saratoga 
Springs in New York, were formerly used industrially. The water from 
these wells brought carbon dioxide to the surface of the earth under a 
pressure of 21 pounds per square inch. As the pressure was released on 
the escape of the water, the gas effervesced and was collected in large iron 
caps placed over the wells in such a manner that the water could escape 
from the lower part. A few years ago, the use of this gas was discontinued, 
and the old factory buildings were removed. It is said, however, that 
interest is again being shown in the commercial utilization of the gas from 
these wells. At Manitou, Colorado, natural gas is being compressed for 
commercial use and it is understood that one or two other- sources in this 
country are being utilized at the present time. 

Considerable attention has recently been given to certain other natural 
sources of carbon dioxide in the United States. A well near Price, Utah, 
produces carbon dioxide about 98 per cent pure and under a pressure of 
760 pounds per square inch. This well is being utilized for making solid 
carbon dioxide on a small scale. Some other wells in eastern Utah and 
western Colorado produce carbon dioxide mixed with petroleum under 
such a pressure that the pipe lines freeze due to the evaporation of the 
carbon dioxide. These wells are sometimes called "ice cream" wells 
because of the appearance of the gas oil mixture. Martin describes an 
interesting well near Tampico, Mexico, which delivered carbon dioxide 
gas under a pressure of about 1000 pounds per square inch. Some solid 
carbon dioxide produced from this gas was shipped to the United States. 

The question of how carbon dioxide came to exist in the earth and the 
conditions under which it does exist, makes an interesting subject for specu- 
lation. Notwithstanding the experimental work which sheds a certain 
amount of light on these conditions, we know practically nothing about it 
at this time. It is quite certain that there are many reactions which 
produce carbon dioxide in the earth and it is not difficult to assign one or 
more of these reactions as the cause of the gas in certain regions. 

As was previously mentioned igneous rocks, calcium and magnesium 
carbonates and bituminous shales, when heated give off carbon dioxide. It 
has been demonstrated that if silica and limestone are put together in boil- 
ing water, calcium silicate and carbon dioxide are produced. 34 The acid 

"Wender, "Die Kohlensaure-Inclustrie." 

88 Martin, J. W., Tnd. Kittj. CJicm., 23, 256-8 (1931). 

a Hapke. Z. komfir. fliiss Case.. 1. 149 (1898). 



CARBON DIOXIDE IN NATURE 29 

produced by the oxidation of metallic sulfidcs by atmospheric oxygen also 
will liberate carbon dioxide when acting on metallic carbonates in the 
earth. 3 - 1 

In some cases, the rate of carbon dioxide production must be the 
same as the rate at which it escapes from the earth. In other cases, how- 
ever, it is quite evident that the supply comes from some sort of reservoir 
in the earth's crust. The nature of this reservoir can only be conjectured. 
We know that many wells deliver carbon dioxide at a rate quite beyond 
all conception as the direct product of a chemical reaction, and in many 
cases under a pressure which must be at least equal to the vapor pressure of 
the liquid. Several other facts lead one to believe that this compound may 
exist as a liquid in rock pockets of tremendous size. Certain wells, e. g., 
the well drilled at Driburg, Germany, in 1894, have been observed to expel 
gas with detonations and the formation of ice in large pieces. Such behavior 
could readily be accounted for on the assumption that the gas came from 
the boiling liquid. That liquid carbon dioxide can exist in nature, was 
demonstrated by Hrewster 30 in 1823, who observed the presence of liquid 
carbon dioxide in mineral cavities. Since that time many investigators 
have made the same observations. 37 

The Carbon Dioxide Balance in Nature. After observing the stu- 
pendous quantities of carbon dioxide that are being added to the atmosphere 
continually from natural gas sources, the question naturally arises as to 
the factors which prevent a serious fouling of the atmosphere with this 
gas. The carbon dioxide in nature represents a dynamic equilibrium, the 
several factors of which tend to increase or to decrease this substance. 
These factors which increase the carbon dioxide in the atmosphere are: 
(1) the evolution of carbon dioxide from springs, gas wells, volcanic vents, 
etc., (2) the combustion of coal, wood and petroleum, (3) the respiration of 
lower organisms, plants and animals, (4) the decay of organic matter, (5) 
certain industrial processes such as lime burning and fermentation. The 
factors which remove carbon dioxide from the atmosphere are: (1) photo- 
synthesis by plants, (2) CaCO 3 -forming organisms, (3) chemosynthesis of 
certain bacteria, (4) the weathering of rocks. 

Factors Increasing Carbon Dioxide in the Atmosphere. The evolu- 
tion of carbon dioxide from wells and springs has already been considered 
because of its economic aspect. It is now best to consider the other factors 
which play a part in the equilibrium reactions involving this gas. 

The combustion of carbonaceous matter adds carbon dioxide to the 
atmosphere in prodigious quantities, yet over a period of a year, its per- 
centage increase from this source is really very small. Sievers 38 estimates 

85 Eaton, A., Am. J. Sci. t 15, 237 (1829). 

Brcwster, David, Trans. Roy. Soc. (Edinburgh), 10, 1 (1823). 

, Vi^/J^K? ***&, P , r ? c * <P% * Soc ' fa ** ")* 17 2" < 1869 >; Hartley, J. Chem. Soc., 29, 
137 (1876) ; ibid., 30, 237 (1876) ; Schorizer, Rudolph, Ccntr. Mineral. Geol', 1920, 143-8. 

88 Sievers, E. G., Gas Age-Record, 51, 757-761 (1923). 



30 CARBON, DIOXIDE 

that in 1920 about 1.317 XlO 9 kilograms or 1.4517 XlO 6 tons of fuel m 
the form of coal of various types such as anthracite, bituminous and lignite 
were produced on the earth. The carbon dioxide formed by the com- 
bustion of this material, assuming a 70 per cent carbon content, amounts to 
about 3.38 x 10 kilograms. In spite of the magnitude of this number, the 
existing carbon dioxide in the atmosphere would be increased only 0.16 per 
cent by its addition if all the opposing factors ceased to operate for that 
period. The carbon dioxide produced by the combustion of wood and 
petroleum would also materially increase this value. The quantity of car- 
bon dioxide produced during one of our great forest fires must be 
enormous. 

The respiration of animals and to a much smaller extent, plants, repre- 
sents vast amounts of carbon dioxide which is being admitted into the 
atmosphere continually. A human being expires, on an average, about 900 
grams of carbon dioxide daily. On the basis of a population of 1750 million 
human beings on the earth, this would add about 629 million tons of carbon 
dioxide to the atmosphere each year, or approximately the same amount 
as produced by burning 230 million tons of coal. Add to this.value the quan- 
tity produced by the respiration of all other animals, both in the sea and on 
the land, and then the comparatively small amount produced by the respira- 
tion of plants and one gets an idea of the magnitude of this source of 
carbon dioxide. 

The decay of organic matter is, for the most part, a chemical reaction 
promoted by microorganisms, carbon dioxide being one of the end products 
of this action. In every acre of fertile soil there are hundreds of pounds 
of living organisms present. Algae, fungi, actinomycetes, and bacteria 
may be considered as plants of microscopic size, while protozoa are micro- 
scopic animals. Millions of microorganisms exist in every gram of fertile 
soil. Leaves, dead plants, and animals all furnish food for these various 
forms of life and the end of it all, including the living forms themselves, 
is carbon dioxide and water which return to the air and to the soil where 
they are ready to go through the cycle again. 

Soil air from fertile areas always has a high carbon dioxide concentra- 
tion. The maximum concentration of this compound was found by You- 
kov 39 to occur 30 cm. below the surface of the soil. This perhaps has no 
significance except to indicate the point of maximum life activity. Heat, 
moisture, nature of the soil, and many other factors affect the situation. 
Marsh 40 observed the rate of evolution of carbon dioxide from fertile soils 
to be from 23.7 to 162.4 mg. per 72 hours from a sample of 500 grams 
of soil. The excellent work of Lundegardh 41 on carbon dioxide evolution 
gives us much information regarding the respiration of soils. The respira- 
tion of agricultural soils in Sweden, varied from 0.125 grams per sq. m. 

Youkov, O. I., Khosiaistvo, 7, 37-46; through Intern. Inst. Agr. (Rome), Bull. Agr. Intelli- 
gence, 1911, 510-1. 

40 Marsh, F. W., Soil Science, 25, 417-54 (1927). 

41 Lundezftrdh. H.. Soil Science. 23. 417-54 (1927). 



CARBON DIOXIDE IN NATURE 31 

per hour for sandy soils low in humus and heavy clay soils to 0.411 grams 
for loams 10 to 15 per cent humus. Forest soils evolve more carbon dioxide 
than agricultural lands. Most of the carbon dioxide of the soil is evolved 
in the surface layer (10 to 15 cm.) and is produced chiefly by microflora. 
Plant roots also produce a considerable quantity, but the amount produced 
by simple chemical oxidation is of no importance. A soil covered with 
oats showed 50 per cent increase in carbon dioxide production over the same 
soil when bare ; but it was shown) by subsequent experiments with sterilized 
and non-sterilized soils that a large percentage of the increase was due 
to bacteria inhabiting the root surfaces rather than to real root respiration. 
The carbon dioxide concentration of soil air (C) is a function of the abso- 
lute carbon dioxide production (A) and the diffusion velocity. The diffusion 
coefficient (K ) is defined by Lundegardh as the volume in cubic centimeters 
of gas which passes through a cylinder 1 sq. cm. on the base by 1 cm. high 
in one second where the difference in partial pressure is 1 atmos. Since 
diffusion is the moving force of soil respiration the diffusion value (K ) 
is an important characteristic and can be calculated by means of the 
equation : 



(3600x(C-0.03)) 



(1) 



in which A a is the total soil respiration in cc. per hour. In general, 
the value of K is an index of aeration, since as carbon dioxide diffuses 
upwards oxygen diffuses downward, and most soils take up the same volume 
of oxygen as the carbon dioxide evolved. Soil respiration shows a seasonal 
variation attaining a maximum in August or September and is associated 
with seasonal variation in bacterial activity. 

Lundegardh found no correlation between respiration of soils and tem- 
perature or rainfall but Suprunenko 42 states that light rains increase, while 
heavy rains decrease, the bacterial activity with a consequent corresponding 
change in the soil respiration. The difference in respiration of sterile and 
non-sterile soils was found by Vandecaveye 43 to be very great. A non- 
sterile soil gave twice as much carbon dioxide as a sterile one. Organic 
manures increase soil respiration markedly and it is believed that a large 
part of the fertilizing value of manures is due to this fact. 

Factors Decreasing the Carbon Dioxide Concentration of the Atmos- 
phere. Without doubt, the process of photosynthesis is the most impor- 
ant factor concerned with the elimination of carbon dioxide from the 
atmosphere. This interesting and important subject has already been 
masterfully treated by Spoehr 44 in his work on "Photosynthesis" and in this 
discussion only a few of its more practical aspects will be considered. 

Photosynthesis is essentially a reducing action in which the oxide of 
carbon is reduced to carbohydrates with the evolution of oxygen and the 

41 Suprunenko, A., through Intern. Inst. Agr. (Rome), Bull. Agri. Intelligence, 1911, 511-2. 
Vandecaveye, S. C., Soil Science, 16, 389-406 (1923). 
Spoehr, H. A., he. cti. 



32 CARBON DIOXIDE 

absorption of energy obtained from the rays of the sun. This reaction takes 
place primarily in the green coloring material in the leaves of growing 
plants and the tree may, therefore, be regarded as a nature-made photo- 
chemical absorption apparatus working on extremely dilute gases. In 
submerged aquatic plants the carbon dioxide dissolved in the water reaches 
the interior of the plant by diffusion through the outer walls of the epi- 
dermal cells. The higher land plants have special differentiated organs 
called stomata, through which the gaseous carbon dioxide passes to the 
chlorophyll-bearing cells. The stomata are minute, mouth-like openings 
in the surface of the leaf, usually situated on the under side. The number 
of openings in a single leaf runs to enormous numbers, a medium sunflower 
leaf containing about 13 million stomata. Some idea of the functioning 
of these minute openings during the gas transfer can be gained from the 
calculation of Noll who finds that a tree weighing 5000 kilograms (5.5 
tons) must have removed the carbon dioxide from about 12 million cubic 
meters (15.6 million cubic yards) of air. 

Another factor tending to decrease the carbon dioxide in the atmosphere 
is the action of rocks during the process of weathering. Some years ago, 
Hunt 45 made the statement, based on a calculation, that the* production from 
orthoclase of a layer of kaolin 500 meters thick and completely enveloping 
the earth, would consume 21 times the amount of carbon dioxide now 
present in the atmosphere. Whether or not this estimate has any numerical 
value, it at least gives some idea of the magnitude of the weathering process. 
It is difficult, if not impossible, to make a reliable estimate of the actual 
amount of carbon dioxide removed from the atmosphere each year by 
these decomposing rocks. A water solution of carbon dioxide may react 
with silicates to produce carbonates or it may react with carbonates of 
calcium and magnesium to form bicarbonates. In the former case, the 
silicates which constitute a large part of igneous rocks, are decomposed 
into simpler and more stable silicates, forming at the same time, carbonates 
of the alkaline earths and the alkali metals. In the latter case, the carbon 
dioxide serves to make the alkaline earth carbonates soluble in water, in 
which condition, they may be transported considerable distances and again 
deposited as carbonates with the liberation of the carbon dioxide. Thus 
bicarbonates formed in the mountains may find themselves finally in the 
ocean where they are washed by the streams and eventually converted 
into sediments, shells, or coral reefs. The carbon dioxide used for the 
formation of bicarbonates is in this way liberated again to the atmosphere, 
but that forming the original carbonates of calcium and magnesium is 
permanently lost, unless conditions change in such a way as to promote 
some of the reactions which are believed to be responsible for carbon dioxide 
wells and springs. Solution and reprecipitation of these carbonate deposits 
may take place again and again by the action of carbonic acid. 

"Hunt, T. Sterry, Am. /. Set. (3), 19, 349 (1880). 



CARHON DIOXIDE IN NATURE 33 

The chemical reactions involved in the process of weathering may be 
illustrated by the equation given by Chamberlin and Salisbury 40 for the 
action of carbon dioxide on labradorite, a typical rock-forming mineral. 
The composition of labradorite is represented by the formula : 

JCaO. A1 2 O ;J . 2SiO 2 
\ Na 2 O. A1 2 O 3 . 6 SiO 2 

Assuming the two molecules represented by this formula to be equally 
abundant, and allowing the whole to be acted upon by water and carbon 
dioxide, we have CaO.Na 2 O.2 A1 2 O 3 .8 SiO 2 +4 H 2 O-f 2 CO 2 = 2(A1 2 O 3 . 
2 SiOo.2 H 2 C ) ) + 4 SiOo + CaC(^ ; , + Na 2 CO 8 . The silicate produced in this 
reaction is kaolin. The carbonates of sodium or potassium usually react 
with other substances and appear as sul fates or chlorides. 

* Chamlicrlin. T. C. f anl Salisbury, R. D , "Oology," Flenry Holt and Co., New York (1909). 



Chapter III 
Physical Properties of Carbon Dioxide 

The active interest shown in carbon dioxide for the past few years has 
been directed very largely towards its chemical and physical properties. 
This interest, however, is not new, investigators since the beginning of the 
science of chemistry have been adding more and more data until at present 
it is exceeding difficult to judiciously select the best and most reliable 
results from the great mass of data. Therefore, in the following discussion 
this shifting operation has been only partially done. In many cases prac- 
tically all of the published data have been recorded and it is left to the 
reader to select those he considers the most useful. 

For the convenience of those desiring data in English engineering units 
many of the tables given in this chapter in metric units have* been calculated 
to the English system. These tables will be found in the appendix at the 
end of this volume. 

Density of Gaseous Carbon Dioxide. The early density determina- 
tions made with this gas were ratios of its weight to the weight of an equal 
volume of air, hydrogen, oxygen or nitrogen, all of course, measured under 
the same conditions of temperature and pressure. The accuracy of these 
determinations depended upon the refinement of weighing equipment and 
technique at that time available yet there is a remarkable agreement between 
these earlier results and values obtained more recently. It is customary 
at present to report the density of gases in absolute values, i. e., the weight 
in grams of one liter of the gas measured under standard conditions of 
temperature and pressure (0 C. and 760 mm. pressure). In Table 4 
these earlier values are listed in their chronological order together with the 
absolute densities calculated from them. 

Relative densities of carbon dioxide, referred to nitrogen, at high tem- 
peratures have been made by Emich. 1 His values were 1.485 at 1000; 
1.497 at 1500 and 1.527 at 2000 C. With carbon dioxide carefully dried 
over sulfuric acid he obtained 1.557 at 19 and 1.550 at 1875 C. 

The absolute density of carbon dioxide has been determined by other 
investigators besides those listed above. Dietrich 2 obtained a value of 
1.9676; Guye and Printza 3 1.9768 and Jaquerod and Perrot 4 1.97677. The 
value most often used at the present time is 1.9769. 5 

1 Emich, F., JLfonatsh, 26, 505 (1905). 

"Dietrich, E., Z. anal Chem. 4, 142 (1864). 

Guye, P. A., and Printza, A., Comfit, rrwr/., 141, 51 (1905). 

4 Jaquerod, A., and Perrot, F. L., Arch Sciences Geneve, (4) 20, 206 (1905). 

"International Critical Tables," 3, The McGraw-Hill Book Co., New York. 

34 



PHYSICAL PROPERTIES OF CARBON DIOXIDE 



35 



TABLE 4. Showing the Absolute and Relative Densities of Carbon Dioxide as 
Determined by Various Investigators. 



Air=l 

1.5245 
1.5282 



H.-1 



1.52037 
1.5191 



1.3822 



1.520 

1 529 

1.529 (at 15) 

1.52897 

1.52856 



22.00 



1.5287 
1.52909 



21.971 



1.530 

1.50 to 1.52 



1.3833 



Wt. of 1 

liter at 

S.C. 

1.9708 
1.9756 
1.9752 
1.9656 
1.9039 
1.9771 
1.9650 
1.97(>7 
1 9767 
1.9767 
1.9762 
1.9745 
1.9763 
1.9768 
1.9767 
1.9780 



Mol. vol. 
at S.C. 

22.345 
22.271 
22.276 
22.385 
22.404 
22.254 
22.391 
22.259 
22.259 
22.259 
22.264 
22.284 
22.263 
22.258 
22.259 
22.245 



Observer 

Berzclius and Dulong 

Marchand 

Marchand 

Wredc 

Regnault 

Mohr 

Exner 

Wiedermann 

Bleekrode 

Crafts 

Cooke 

Cookc 

Lcduc 

Raylcigh 

Guye 

Strutt 

Drenteln 



Note. Calculations were made on the basis of Air=1.2928, Hydroften=0 08987 and 
Oxygen=1.4290 grams per liter measured under standard conditions (760 mm. pres- 
sure and C.). 

REFERENCES 

Berzelius, J. J., and Dillons, P. T.., Ann. chiin. fihys. (2) 15, 386 (1820). 

Marrhand, R. l". t /. fiiakt. Chem. (1) 44, 38 (18-18). 

Wrede. F. J., Scand. Nat. Forh., 2, 242 (1841); Pong. Ann. 52, 225 (1841). 

Renault, H. V., Mem. acad. 26, 701 (1863). 

Mohr, F., Bcr. 4. 149 (1871). 

Exner, E., Pong. Ann. 155, 321. 443 (1875). 

Wicdcmann, E., Pogn. Ann. 157, 1 (1876). 

Bleekrode, L. f Proc. Roy. Soc. (London) 37, 339 (1884). 

Ctafts, J. M., Comfit, rend. 106, 1662 (1888). 

rooke, J. P., Am. Chcm. J. 11, 509 (1R89). 

Leduc, A., Comfit, rend. 125, 571 (1897); Cowfip. rend 176, 413 (1898). 

Lord Rayleigh, Proc. Roy. Soc. (London) 62, 204 (1897). 

Guye, P. A., Comfit, rend. 112, 1257 (1891); 144, 976, 1360 (1907); /. chim. fihys. 5, 203 (1907); 

Bull. soc. chim. (4) 5, 339 (1909). 

Strutt, R. J., Proc. Roy. Soc. (London) 68, 126 (1901). 
Drenteln, Z. fihysik. eh-cm. Unterricht 17, 350 (1904). 

The change of density with temperature and pressure variations has 
been calculated by Parr 8 and the results of these calculations are given in 
TableS. 

The density of dry saturated carbon dioxide vapor at various tempera- 
tures has been the subject for numerous researches. A tabulation of the 
results of these measurements has been made by Plank and KuprianofT 7 
and is shown here as Table 6. The last column of this table shows the 
most probable density values. 

Density of Liquid Carbon Dioxide. Thilorier 8 was one of the first to 
attempt specific gravity determinations on liquid carbon dioxide. His 

6 Parr, S. W., 7. Am. Chem Soc., 31, 237 (1909). 

T Plank, R. and Kuprianoff , J., Z. ges. Kdlte-Ind. Beihefte, 1, 1 (1929) 

Thilorier, M., Ann. chim. phys., (2) 60, 427 (1835). 



36 



CARHON DIOXIDE 



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K " 

x) 21 tx CO 00 00 Ix Ix Ix tx, Ixlx Ix tx Ix tx Ix O NO O NO NO O ^O tx 00 OO OO OO OO OO OO 00 OO 00 Ix tx tx |x Ix tx tx Ix tx tx NO 

Q *- ~ - ~ *-< ~ ^ ~ ^ ^ - 1 - 1 ~ -"--"---'-'-' ^ _ _ ^ ^^_^^ T _^^ rHr H rHT - l 

C7) O 

V. V t^OOCO^^txlxSt^^lx'lx!rxrx' 3vONON0 1 NONONO ^OOOOCOCOOOOOOOOOCOtx Ix-tx Ix Ix! Ix tx Ix! tx Ix Ix \O 

xi "O T^,-^^^^^,^,^^^^^,!,.^^^^^^^^^ r-1 il r^ i I i-l . I r-l . 1 r-t r-1 i I . lr-ijir-lT-1r-1r-ii-1r-1r-1 

2 ! 

"x? . J O O O\ 00 tx NO if) -< *+ ro Cv) -( O O\ CO Ix NO ""> -t f 1 ^1 in 'x vO >O -t- ri -j ^1 r-t O ON OO tx O 10 -f *r< ro O-J --H O O\ 

~ T i,; OOOOIx txtxlxtxtxtxtxtxlx tx vO -ONONONO ONO O (^ 00 30 CO OO OO CO 00 OO 00 tx tx t x tx tx I x tx tx Ix Ix Ix NO 

*< * ^^j^;,.;,.;,-!,^,-;^,-;^..;^,.;^^!^,-;,.;^!^; ^ 1 _;^^^^ r 4^; r _j^^ 1 _^ r _; T _; P 4 r ^^^ T _j I _; r _; 

* '^ 

O rH Q ro iO txoO O r-l "^ *^ *O Ix OO ON O i f^| ro ro *! rf O iO \o OO O r 1 *1" "4 VO 00 ON O < ^J tf t r 1 "t" ! "1 lr > O m m 

*"* 'o *^ OO txtxjx txix tx tx txlxlxtx Ix VO \O NO NO NO ' NO NO ix O OO CO CO CO OO QO Ix Ix tx tx tx Ix tx Ix Ix tx tx VO N5 

*H" \ 

V^\ I 2S o\ O\ OO Ix *O r* -f "J 'O t^l " O ON 00 I x NO 10 *f -f ff ' <*! in *& l "*" r< ^ r> ' rx ' *"* ^3 ON OQ ix vO >O *1" rr * rr t ^J -* O ON- CO 

i. J s6 rt J tx tx tx tx Ix Ix Ix tx tx tx Ix tx VO vO NO NO NO O O NO O Jx OO OO 00 OO CO 00 CO Ix I x Ix Ix Ix r x I x Ix Ix Ix tx vO O 

o "o 

iM C .,, ro'OtxOOOOirO't'VOtxOOO' "(NicofO^iOin'Oto (\I OOO ir*}-1-inixOOONOrHr|rO'1- 1 ^-OiO'ONOvONO 

W fSi O\OOtx\ONOiO-t' r *'N'-<OOO\OOIxNOiO'J-rOf s Ii-H in OiO'TrOP>lr-iOONCOOOtx\OO'1-rof^Ji-iOO\OOlx 

J "d tx |x Ix tx Ix tx tx tx tx tx Ix Ix tx NO vO NO NO NO NO O NO <O t> . 00 OO OO 00 OO 00 CO tx Ix Ix Ix tx tx Ix tx tx tx tx VO NO NO 

OQ We/) _J_J f _J t _J,_J f ^_J r H r ^ r 4^4 t _J f _J l _I p J T _J r 4 I _J t _J 1 _J f ^ .li-1r-1r-1ilr-lT-lr-1r-1.-ir-l.|r-|r-1i-1r-1.li-li-1.i.l 

^ fOON'O^vO-HinoO-Hmr^forqOl fOtxO- ON-fOO^vOO\fM-t-OIxtxlxNO-l-HVOO-1-NOI NO 

'!** 

Q*O rsi f*StOtxO\OtNlfO | OvOtxO\O-t<siPO'tiO^O < OvONO OO OOO-H'*>*t - SOIxCOO\OrH(\|r*lfiOiONONOvOtxtx 

C rv OOlxNOtOO' l l-*S' N lf-OO\O\OOtxVOO't'*O'^l-O * ^"f'*J< > N>-HOO\COIxIxVO*O^t / lP'<l' lOONOOtxvO 

.o S Ix! "h^^^h^ 1 ^^???^^^?^^^? ^ 00 . 00 . ( 00 . o i> : l> : l ': t> : l> : l> : l ': t> : t> : l> :^ vo .^ v0 . v0 . 

s| 7 

s" 

O<0 CONO*Ofx'^OOf*;lx>-i'l-NOlxOOtxtOf*SO\*NO'aO O\'fO\1-OO-i-rixO\i-i-i-iOOONOP<JNOOrqc*jro 

m 3 e OOO< v lt ir >txOOo i - |r ^t 1|/ ^ v O s OOO\OO-t-i-< VO rOONOOOO\-ifvirorJ-vOlxOOO\O\O-it-irv|rifMO) 

2 O S txlxvOOtfj<M?Ti!-HOONOOIxvO>O'r-J-rorjt-iO rt- 'l'f*'N-'OOO\OOlxvom'*- r O^|C*lr-iOO\OOtxNO 

E V J>I lxixtxtxlxlxlxt>.rxtxvOONONONONONONONONOvO tx OOOOOOoqcOOO Ixtxtxrxi>rxrxtxtxtxtxvOvOvovo 

.> s" 

1^ i i ; i i ; ! i i ! ! i i i i i i i i i i i ; i i ; ; ! i i i ! i i i i ; ; ; i i i 

JTJ d a 

tJ BO'-rvi*>-fnvOlxOOO\O-Hrlro-tinNOlxoOO\C 



PHYSICAL PROPERTIES OP CARBON DIOXIDE 



37 



TABLE 6. Density of Dry Saturated Vapor of CO 2 at Various Temperatures. 

(Data in gm./cc.) 



Temp. 


experimental values- 

Caillutet 
and Aniagat 
Muthias 


^ r 

Lowry 
and 
Erickson 


Jcnkin 
and 
Pyc 


M oilier 


- v. iiicuiaic 
Lauren 


'U VU1UC3 

Eichcl- 


Kcycs 
and 
Kenney 


Plank 
and 
Kupri- 
anoff* 


31 


0.396 


0.392 


0.468 










0.460 


0.392 


30 


.354 


.334 


.338 




.338 


.333 


.338 


.337 


.334 


25 
20 


.254 
.203 


.240 
.190 


.237 
.191 


.196*' 


.239 
.191 


.239 
.194 


.239 
.191 


239 
.188 


.240 
.190 


15 


.167 


.158 


.159 




.159 


.160 


.159 


.152 


.158 


10 


.139 


.133 


.135 


.138 


.133 


.134 


.133 


.132 


.133 


5 


.117 


.114 


.115 




.113 


.113 


.113 


.109 


.114 





.099 


.096 


.099 


.100 


.096 


.096 


.098 


.096 


.096 


- 5 


.085 




.085 




.082 


.082 


.083 


.082 


.082 


-10 








.073 


.070 


.072 


.070 




.070 


-15 










.060 


.061 


.060 




.060 


-20 








.053 


.051 


.052 


.051 




.051 


-25 










.044 


.044 


.044 




.044 


-30 








.038 


.037 


.037 


.037 




.037 


-35 


9 










.031 


.031 




.031 


-40 








.026 




.026 


.026 




.026 


-45 












.022 


.022 




.022 


-50 








.018 




.018 


.018 




.018 


-55 














.015 




.015 


-56.6 


















.014 


* Amagats data 


to C. 

















values were as follows : 4-30 -0.60, O n -0.83 and -20 n -0.90. D'Andreef 9 
made a number of determinations between 10.82 and 25.38 C. and 
developed an equation to represent the change of specific gravity with tem- 
perature. His results do not agree at all with those obtained by later 
investigators and at present are considered to have but little value. A few 
of these determinations are as follows : 

Temp. C -10.82 -5.02 -0.84 +4.22 -U0.08 +14.79 +20.85 +25.38 

Observed 0.9985 0.9712 0.9500 0.9265 0.8938 0.8657 0.8209 0.7790 

Calcd 0.9989 0.9708 0.9510 0.9262 0.8939 0.8652 0.8201 0.7801 

The calculated values were olrtaincd from the equation: D 0,94005 
-0.0048041 /- 0.00002936 / 2 -0.0000019409 f\ In 1886 Cailletet and 
Mathias made a series of determinations on the densities of various liquefied 
gases and their saturated vapors. While they extended the measurements 
down to 23 C. for carbon dioxide their results are rather erratic and do 
not serve to plot a smooth curve. They obtained the following results: 



Temp. C. ... 


-23 


-5 


+0.5 


+ 10.1 


+ 15.7 


+ 19.7 


+25.0 


+30.0 




D of vapor. . . 


0.057 


0.085 


0.0983 


0.141 


0.171 


0.201 


0.254 


0.354 




Temp. C. ... 


-34 


-25 


-11.5 


-1.6 


+ 1.3 


H 6.8 


+ 11.0 


+ 15.9 


+22.2 


D of liquid . . 


1.057 


1.016 


0.966 


0.910 


0.907 


0.868 


0.840 


0.788 


0.726 



9 D'Andreef, M. E., Ann. clnm. fihys., (3) 56, 317 (1859). 



38 CARBON DIOXIDE 

The classical researches of Amagat 10 have given us the most widely used 
values above C. and those of Behn 11 have extended the data for the 
liquid density down to 60 C. Table 7 gives the results obtained by 
Amagat for both liquid and its saturated vapor. Behn's values for the 
liquid were as follows: 

Temp. C +30 +20 +10 -10 -20 -30 -40 -50 -60 

Density 0.598 0.772 0.860 0.925 0.981 1.031 1.075 1.116 1.154 1.191 

TABLE 7. Showing the Density of Liquid Carbon Dioxide and 

its Saturated Vapor Together with the Vapor Pressure 

from to its Critical Temperature. 

(Data by Amagat) 

T emo Density of Density of Vapor 

o pP* liquid vapor pressure 

gm./cc. gm./cc. atmos. 

0.914 0.096 34.3 

1 0.910 0.099 35.2 

2 0.906 0.103 36.1 

3 0.900 0.106 7.0 

4 0.894 0.110 38.0 

5 0.888 0.114 39.0 

6 0.882 0.117 40.0 

7 0.876 0.121 41.0 

8 0.869 0.125 42.0 

9 0.863 0.129 43.1 

10 0.856 0.133 44.2 

11 0.848 0.137 45.3 

12 0.841 0.142 46.4 

13 0.831 0.147 47.5 

14 0.822 0.152 48.7 

15 0.814 0.158 50.0 

16 0.804 0.164 51.2 

17 0.796 0.170 52.4 

18 0.786 0.176 53.8 

19 0.776 0.183 55.0 

20 0.766 0.190 56.3 

21 0.755 0.199 57.6 

22 0.743 0.208 59.0 

23 0.731 0.217 60.4 

24 0.717 0.228 61.8 

25 0.703 0240 63.3 

26 0.688 0.252 64.7 

27 0.671 0.266 66.2 

28 0.653 0.282 67.7 

29 0.630 0.303 69.2 

30 0.598 0.334 70.7 
30.5 0.574 0356 71.5 
31.0 0.536 0.392 72.3 
3125 0.497 0.422 72.8 
31.35 (Critical data) 0.464 0.464 72.9 

Amagat, E. H., Com ft. rend., 114, 1093 (1892). 
"Behn, U., Ann. physik. (4), 3, 733 (1900). 



PHYSICAL PROPERTIES OF CARBON DIOXIDE 39 

In 1920 Jenkin 12 published the following data for the density of 
liquid carbon dioxide : 

Temp. C ........... +25 20 15 10 5 

Density ............. 0.717 0.761 0.819 0.861 0.894 0.925 

Lowry and Erickson 13 recently made some very careful determinations 
of the densities of coexisting liquid and gaseous carbon dioxide. Their 
values arc : 

Density of Liquid Carbon Dioxide 

Temp. C. .. +31 +30 +25 +20 +15 +10 +5 -5 
Density ..... 0.4683 0.6016 0.7165 0.7784 0.8236 0.8626 0.8966 0.9273 0.9556 

Density of Gaseous Carbon Dioxide 

Temp. C. .. +31 +30 +25 +20 +15 +10 +5 -5 
Density ..... 0.4683 0.3380 0.2375 0.1910 0.1594 0.1350 0.1154 0.0993 0.0854 

Values calculated from the equations 

"0 ....... (2) 



ZV=0.4683+0.0014420 fc -/) -0.1318V (t k -t) ....... (3) 

agree very well with the above data. It will be observed that according to 
the data of these investigators the critical density of carbon dioxide is 
0.4683. 

Density of Solid Carbon Dioxide. Solid carbon dioxide is usually 
made in the form of very fine crystals resembling snow and for that 
reason is called carbon dioxide snow. The density of this material depends 
upon the method of its production and upon the pressure to which it is 
subjected. This compound can be frozen in the form of a transparent, 
glass-like solid and in this condition has its maximum density at any one 
temperature. Landolt 14 found values for the compressed snow from 1.188 
to 1.199. Bleekrode 15 obtained 1.3 to 1.6 and Schwalbe 16 1.19. Bchn 17 
sublimed carbon dioxide under normal pressure into a space cooled 
below 79 C. and the gas condensed slowly into a transparent mass. Some 
of these masses weighed from 30 to SO grams and had a density of 1.56. 
In a series of determinations carried out with slightly greater precision 
he obtained an average of 1.53. Dewar 18 obtained 1.6267 at 188.8 and 

M Jenkin, C. F., Proc. Roy. Soc. (London), 98, 170 (1920). 

18 Lowry, H. H., and Erickson, W. R., /. Am. Chem. Soc., 49, 2729-2734 (1927). 

"Landolt, H. f Bcr., 17, 309 (1884). 

"Bleekrode, L., Proc. Roy. Soc. (London), 37, 339 (1884). 

"Schwalbe, B. f Z. physik. chem. Unterricht. 9, 1 (1896). 

" Behn. U. f Ann. Physik. (4), 3, 733 (1900). 

"Dewar, J., Chcm. News, 85, 277, 289 (1902); ibid., 91, 216 (1905). 



40 CARBON DIOXIDE 

1.53 at the boiling point. Recent determinations made by Maass and 
Barnes 19 cover a considerable temperature range. Their values are: 

Temp. C -56.6 -60 -65 -70 -75 -80 -85 -90 

Density kg./l. ...>.... 1.512 1.522 1.535 1.546 1.557 1.566 1.575 1.582 
Density lbs./cu. ft 94.39 95.01 95.83 96.51 97.20 97.76 98.32 98.76 

Temp. C -95 100 110 -120 130 -183 

Density kg./1 1.589 1.595 1.606 1.616 1.625 1.669 

Density lbs./cu. ft 99.20 99. ;7 100.2 100.9 101.4 104.2 

The current practice of making solid carbon dioxide for the trade is to 
compress the snow or to cause the crystals of solid to freeze together by 
the expansion of liquid at the triple point or to combine these. KuprianoiT- 
conducted an exhaustive research under conditions similar to these in which 
the density was determined as a function of the pressure and time of press- 
ing. Because his data are easily applied to the practical operation of solid 
C(X formation his results are considered in a later chapter (cf. page 209). 

Molecular Weight. Tt is of interest to note that Berthclot 21 as early 
as 1898 obtained a value for the molecular weight of carbon dioxide which 
is identical with the formula weight accepted at present. Thfe was obtained 
by calculation from the relative density of 1.38324, referred to oxygen, and 
on the basis of oxygen being 32. Lord Kayleigh 22 working at C. and 
760 mm. pressure obtained a value of 44.268 and at low pressures a value 
of 44.014. Jacquerod and Perrot- :t obtained 43.W2 at 1067 C. and Lowcn- 
stein 24 while determining the percentage dissociation at higher tempera- 
tures found 43.8 at 1350 C. The molecular weight of 44.004 recently 
obtained by Cooper and Maass 25 is without doubt the most reliable on 
record. 

Molecular Volume. From the accepted formula weight of 44.0 and 
the absolute density of 1.9760 (according to Parr) one calculates the 
volume occupied by 44 grams of carbon dioxide gas at C. and 760 mm. 
pressure to be 22.267 liters. Bridgeman considers 22.2613 liters to be 
the most likely value for this constant. 

Molecular Diameter. Jeans 20 has calculated the molecular diameter 
of carbon dioxide by four different methods with the following results : 

From viscosity measurements 3.47 X 10~ 8 cm. 

Prom conductivity of beat 3.58 X 10' 8 cm. 

From coefficient of diffusion 3.27 X 10 " 8 cm. 

From deviation from Boyle's law 3.00 XlO" 8 cm. 

* Maass, O., and Barnes, W. II., Proc. Roy. Soc. (London). A 111, 224 (1926). 
^Kuprianoff, J., "IVher die TIerstellun< von fester Kohleiisatue," Berlin (1931). 
"Berthelot, D., Compt. rend., 126, 1415 (1898). 
"Lord Rayleigh, Proc. Roy. Soc. (London), 62, 204 (1898). 

23 Jacquerod, A., and Perrot, F. I.., ^WM r/iiwi. phys., 140, 1542 (1905). 

24 Lowcnstein, L., Z. fihysik. Chcm., 54, 707 (1906). 

Cooper, D. LeB. and Maass, O., Can. J. Rcseanh, 4, 283-98 (1931). 
28 Jeans, J. H., Phil. Ma<j., (6) 8, 692 (1904). 



PHYSICAL PROPERTIES OF CARBON DIOXIDE 41 

Giving double weight to the viscosity determinations he obtained a mean 
value of 3.36xlO~ lS cm. Robinson- 7 by measurement of the absorption of 
cathode rays by carbon dioxide calculates a value of 3.44 x 10" 8 cm. while 
Hasse and Cook 2N from viscosity data recently obtained a value of 
3.55 x 10- 8 cm. 

Molecular Velocity. Blascrna 20 calculated the velocity of carbon 
dioxide molecules at various pressures and temperatures. Some of his 
values were as follows where V is the velocity in meters per second: 

Pressure cm. of Hg. . 76 100 500 1000 1500 2000 

V at 3.3 393.3 392.1 391.8 385.0 374.5 362.9 350.4 

V at 100 459.7 459.2 459.0 456.4 452.8 449.4 446.2 

Mean Free Path. This value as calculated by Jeans 30 is 4.0 x 10- cm. 

Velocity of Sound in Carbon Dioxide. Buckendahl 31 gives the fol- 
lowing values for the velocity of sound in carbon dioxide : 

Temp. C 100 300 500 670 945 1080 

Meters/sec *..... 258.04 301.54 373.74 434.06 503.28 543.29 572.45 

Knescr 32 found that the velocity of sound in carbon dioxide increases 
with the frequency in the range from 0.5 x 10 3 to 3.0 x 10 5 cycles per 
second. Above the frequency of 3 x 10 r ' cycles the velocity is again con- 
stant at the value of 2(>S.2 meters per second at ordinary temperature. 

Viscosity. The resistance to flow of carbon dioxide has been 
determined by many different methods. Those most generally used are : 
(1) time required for a certain quantity of gas to flow through a small 
orifice, (2) the oil drop method, and (3) a method based on the deflection 
of a stationary cylinder inside a whirling one. Viscosity measurements may 
be expressed in relative units where air is taken as the standard of measure- 
ment or in C.G.S. units which are called "poise" and usually designated as 
rj. Some of the relative values obtained by various investigators at a 
pressure of 760 mm. are as follows : 

Observer Value Reference 

Kundt, A. and Warburg, E. 0806 Il'icd. Ann., 17, 390 (1882). 

Graham, T. .807 Phil. Trans., 136, 573 (1846). 

Maxwell, J. C. .859 Phil. Trans.. 156, 249 (18C6). 

Crookcs, W. .9208 Proc. Roy. Soc. (London), 31, 446 (1881). 

Hofsass, M. .840 /. Gasbel, 62, 776-7 (1919). 

"Robinson. J., Proc. Uin:: Durham Phil. Soc., 3, Pt. 4. 195-200. 

38 llas.se, IT. K., and Cook, W. R. f Phil. Man, (7) 3, 977-90 (1927). 

"Blaserna, P., Compt. rend., 69, 134 (1869). 

80 Jeans, J. II., "The Dynamical Theory of Cases," Cambridge (1916). 

81 Buckendahl, O., "Ueber SchalltfeschwimliRkeit ami Verhaltnis der snc/ifischen Wartnen 
von Kohlensaure unrt Stickstoif hoi gewohnlicheii utul huhcn Tempetaturcn," Heidelberg (1906). 

a Kneser, II. O., Phytik. Z, 32, 179 (1931). 



42 



CARBON DIOXIDE 



Table 8 gives values of y obtained by various investigators at 760 mm. 
and the temperature indicated : 



TABLE 8. Values of TI Obtained by Various Investigators. 



Temp. fl 








TjXlO 4 

1.64 

1.383 

1.366 (CO, and N 2 O) 

1.382 



15 1.441 (CO a andN 2 0) 

23 1.490 

23 1.471 

23 1.478 

23 1.472 

100 1.859 

100 1.845 (CO a and N 2 O) 



Observer 
Meyer, O. E. 

Wiiller, A. 
Smith, C. J. 
Klemenc, A. and 

Kemi, W. 
Smith, C. J. 

Lasalle, L. J. 
Ishida, T. 
Eglin, J. M. 
Van Dyke 
Wiiller, A. 
Smith, C. J. 



Reference 

"Die kinetische Theorie der 

Case, 11 Breslau (1877). 
Wied. Ann., 4, 321 (1878). 
Proc. Phys. Soc. (London) , 34, 

155-64 (1922). 
Monatsh, 44, 307 (1924). 
Proc. Phys. Soc. (London), 34, 

155-64 (1922). 

Phys. Rev., (2)17,354(1921). 
Phys. Rev., (2) 21, 550 (1923). 
Phys. Rev., 22, 161-70 (1923). 
Phys. Rev., 21,250(1923). 
Wied. Ann. f 4, 321 (1878). 
Proc. Phys. Soc. (London), 34, 

155-64 (1922). 



The change of viscosity with a change in temperature is expressed with 
a fair degree of accuracy by the equation of Sutherland, 3 ^ which may be 
written 

T ' +C T 



T, 




1.50 1)110* 

FIGURE 1. Viscosity 
Sutherland, W. f Phil. Mag., (5) 36, 507 (1893). 



1.70 1.80 

Curve of Carbon Dioxide. 



PHYSICAL PROPERTIES OF CARBON DIOXIDE 



43 



where rj is the viscosity coefficient at the absolute temperature T and rj 
is the coefficient at absolute temperature TO while C is a constant. The 
value of C for carbon dioxide has been reported as 277 by Sutherland, 
239.7 by Breitenbach 34 and 263.4 by Klemenc and Remi. 

Figure 1 shows a curve drawn with the most probable values of y thus 
far reported between and 100 C. Unfortunately the number of deter- 
minations is very limited, in fact hardly sufficient to determine the course 



FIGURE 2. 


Showing the Change of 

Viscosity of Carbon Dioxide 

with a Change of Pressure. 

(Data by Phillips) 




of the viscosity curve. Values for y obtained by calculation with Suther- 
land's equation, using 263.4 for the value of C, are also plotted and the 
curve represented by the dotted line. It is rather interesting to note that 
the use of any of the other values for C, listed above, improves the agree- 
ment between these curves but slightly. 

The change in viscosity of carbon dioxide with a change in pressure has 
been studied at several different temperatures by Phillips. 35 His results 
are tabulated in Table 9 and the curves constructed from these data are 
shown in Figure 2. It is of interest to note that in Figure 2 the curves 

14 Breitenbach, P., Ann. Physik., (4) 5, 166 (1901). 
"Phillips, P., Proc. Roy. Soc. (London), 87 A, 48 (1912). 



44 



CARBON DIOXIDE 



TABLE 9. Showing the Change of Viscosity of Carbon Dioxide ^vith a 
Change in Pressure. 

(Data from Phillips) 



p 

atmos. 


Viscosity 
T]Xl0 4 poi"sc 


Density 


P 

atmos. 


Viscosity 
T]Xl0 4 poise 


Density 


20 C. 


30 C. 


83 


8.23 


0.835 


110.5 


7.70 


0.795 


72 


7.71 


.812 


104 


7.33 


.781 


59 


6.97 


.768 


96 


6.93 


.760 


56 


1.86 


.190 


90 


6.43 


.743 


50 


1.77 


.145 


82 


5.92 


.716 


40 


1.66 


.100 


80 


5.65 


.706 


20 


1.56 


.036 


76 


5.29 


.680 


1 


1.48 


.00183 


74 


4.95 


.064 








73 


4.78 


.653 








72 


4.58 


.635 








70 


2.29 


.287 








60 


1.87 


.177 








40 


1.68 


.092 








20 


1.59* 


.0354 








1 


1.53 


.00177 


32 C. 


35 C. 


120 


7.88 


0.790 


114.5 


6.93 


0.755 


112 


7.41 


0.777 


109 


6.60 


.741 


104 


6.95 


.760 


96 


5.86 


.696 


93 


6.27 


.729 


88 


5.11 


.653 


87 


5.86 


.700 


85 


4.56 


.626 


84 


5.60 


.682 


80 


3.61 


.494 


80 


5.28 


.655 


75 


2.37 


.289 


76 


4.88 


.597 


70 


2.14 


.227 


75 


4.06 


.555 


60 


1.78 


.163 


74 


2.54 


.360 


40 


1.74 


.085 


70 


2.14 


.255 


20 


1.63 


.0348 


60 


1.87 


.170 


1 


1.56 


.00174 


40 


1.75 


.090 








20 


1.62 


.0352 








1 


1.55 


.00176 








40 C. 




112 


5.71 


0.699 








108 


5.40 


.682 








100 


4.83 


.636 








94 


4.14 


.582 








85 


2.69 


.385 








80 


2.18 


.291 








70 


2.00 


.204 








60 


1.87 


.153 








40 


1.76 


.083 








23.8 


1.69 


.0408 








1. 


1.57 


.00173 









PHYSICAL PROPERTIES OF CARBON DIOXIDE 45 

cross before the gas is liquefied which indicates that the substance begins to 
act like a viscous liquid before condensation takes place. The portion of 
the curves AB and A'l" indicated with dotted lines represent the viscosity 
of a superheated liquid and the part represented by CD and C'D' represents 
the viscosity of a sui>ercooled vapor. The critical viscosity is 3.21 x 10~ 4 
and the critical density 0.464. 

Coefficient of Diffusion. The Stefan-Maxwell 30 basic differential 
equation for the diffusion of one gas A into another B is 

D dpA 



wherein />. t and />/* are the partial pressure (or mole fractions) of gas A 
and gas B respectively, z is a length measured in the direction of diffusion, 
K 4 \ is the "current density" or net rate of diffusion of gas A per unit area, 
and D is the "diiTusivity" or specific diffusion coefficient for the gas system 
which is substantially independent of the relative concentration of the com- 
ponents. Obviously, the net units of D must depend on those chosen for 
R.\. Thus if Tv'.t is expressed in gram moles per sec. per sq. cm., D must 
be expressed in gram moles per sec. per cm., the units for p being imma- 
terial because of the ratio "rf/>.i //>." 

The variations of D with temperature and pressure changes may be 
expressed by the Loschmidt- von Obermayer 37 equation which one may 
write in the following form 



Tn this equation 7) is the coefficient of diffusion at absolute temperature T 
and pressure /> while A> is the value of D at T (=273 A') and />o 
( = 1 atmos.). /// is a constant having a numerical value which may be 
taken as 1.75 or 2.00 depending on the nature of the gases involved. The 
values of D {} for carbon dioxide and the gases indicated are as follows: 

A-"\ 
Gas D [ --- 1 Observers 



/cm.*\ 
DA - - 
\ sec. / 



Hydrogen 0.550 175 Loschmidt, von Obennayer and Schmidt. 

Carbon monoxide ... .137 1.75 Loschmidt, von Ohermaycr. 

Oxygen 139 2 00 Loschmjdt, von Obermaycr. 

Nitrous oxide 096 2.00 Loschmidt, von Obermayer. 

Air 138 2.00 Loschmidt, von Obermayer and Waitz. 

Methane 156 2.00 Loschmidt. 

The coefficient of diffusion of bromine in carbon dioxide has been mea- 
sured by Mackenzie and Melville, 38 and a very recent set of calculations 

"Stefan. J., Sitsbcr Akad. tt'iss. f/rrn, 65, an.l 74, 161 (1879); Maxwell, J. C., Phil. Mag., (4) 
35, 199 (1868); Phil. Trans., 157, 49 (1867); Set. /'<!/>., 2, 26. 

"Loschmidt, J., Sitabcr. Akad. ll'iss. H'trw.. 61. 367 (1870); ibid., 62, 468 (1870); von Ober- 
mayer, A., ibid., 81, 1102 (1880); ibid., 85, 147, 748 (1882); ibid. t 87, 188 (1883). 

88 Mackenzie, J. E., and Melville, H. W., I'roc. Roy. Soc. (Edinburgh), 52, 337-44 (1932). 



46 CARBON DIOXIDE 

of diffusional coefficients for several gases and carbon dioxide have been 
made by Roth. 30 This last investigator points out that the diffusion veloc- 
ity is not exactly inversely proportional to the square root of the densities 
as is stated in Graham's law. If this were so the expression kMiXM2 9 
in which MI and M* are molecular weights of the gases, would be constant. 
Actually, however, the values for this expression for the mixing of carbon 
dioxide and air, hydrogen, carbon monoxide, methane and water are: 
5.05, 5.10, 4.62, 3.87 and 3.72 respectively. Roth developed the follow- 
ing expression for calculating the content, gi, of one gas in another as a 
function of time : 



01 = 0* + - - - - - + / 

V 

kzq 1 1 
the exponent .r is equal to -- X -- 1 . 

/ Vi 7'2 

In this equation </] and g^ are the initial contents, v\ and z/2 the respective 
volumes, s the time in seconds, q the section of gas considered and k a 
factor. The values for k in several gas mixtures are as follows : CCVair, 
0.142; COo-hydrogen, 0.544; CO 2 -carbon monoxide, 0.131; CO 2 -methane, 
0.146; and CCVwater vapor, 0.132. 

Diffusion Through Solids. The transference of gases through solid 
partitions should be essentially the same as simple diffusion through a 
porous plate, provided that these rates are not complicated by adsorption or 
solution of the gas in the solid material. In such simple systems the rates 
of penetration are approximately inversely proportional to the viscosities 
of the gases. The phenomenon of simple diffusion through porous material 
has been investigated by Graham and also by Matteucci, 40 who studied the 
rate of diffusion of carbon dioxide through dry plaster of Paris and by 
Roscoe 41 who determined the rate of passage of carbon dioxide through 
bricks. The rate of diffusion of carbon dioxide through soil has been 
studied by Hannen. 42 While this is not a case of simple diffusion, due to 
the many other factors which must be considered, it is nevertheless of con- 
siderable importance, especially from the point of view of plant food. 

The penetration of rubber by various gases, especially carbon dioxide 
and hydrogen has received considerable attention from research workers. 
As pointed out by Graham 43 the relative rates of penetration of rubber by 
different gases bears no relation to their densities nor to their viscosities. 

"Roth, Walter, Arch EisenhZttenw., 8, 401-3 (1935). 

Graham, T., Phil. Maq., (4) 26, 409 (1863) : ibid., f4) 32, 401, 503 (1866) ; Proc. Rov. Soc. 
(London), 12, 611 (1863); /. Chem. Soc., 20, 235 (1867). Matteucci, C., Arch. Sci. Geneve, "(2) 18, 
103 (1863); Bull. soc. chim., (1) 5, 546 (1863); Comfit, rend., 57, 251 (1863). 

* Roscoe, H. S., J. Chem. Soc., 10, 251 (1857). 

Hannen, F.. Biedermann's Zentr., 22, 74 (1893). 

41 Graham, T., he. cit. 



PHYSICAL PROPERTIES OF CARBON DIOXIDE 



47 



He postulated that the penetration mechanism consisted in the solution 
of the gas on one side of the rubber, with a subsequent diffusion of the 
dissolved gas through the sheet and vaporization on the other side. This 
explanation is pretty well accepted at present. 

Edwards and Pickering 44 in a carefully planned series of experiments 
determined the permeability of rubber to carbon dioxide and to other gases. 
They were able to show that for any one gas the rate of penetration through 




Carbon DioxicU n Air. Per Cant 

FIGURE 3. Relation Between Permeability and Partial 
Pressure of Carbon Dioxide. 

(According to Edwards and Pickering) 

a given sample of rubber is directly proportional to the partial pressure 
difference and increases rapidly with temperature. In Figure 3 the diffusion 
curves of carbon dioxide through a sample of rubber and a piece of balloon 
fabric have been plotted and Figure 4 shows how the rate of diffusion 
changes with the temperature for carbon dioxide, hydrogen and helium. 
The effect of solubility on penetrability has been studied by Venable 
and Fuwa. 45 They found that the carbon dioxide held by rubber formed 
a true solution and the amount of gas thus held, within the limits investi- 

44 Edwards, J. P., and Pickering, S. F., Chem. Met. E*g., 23, 17-21, 71-75 (1920). 
Venable, C. S., and Fuwa, T., Ind. Eng. Chem., 14, 139-142 (1922). 



48 



CARBON DIOXIDE 



gated, was directly proportional to the pressure and was unaffected by the 
degree of vulcanization or the presence of compounding ingredients. It 
was also found that the solubility of carbon dioxide in rubber decreased 
rapidly with a rise of temperature. This change is clearly shown by means 




-10 



100 



BO 40 60 30 

Temperature G. 

FIGURE 4. Relative Permeability of Rubber to Carbon Diox- 
ide, Hydrogen and Helium at Various Temperatures. 

(According to Edwards and Pickering) 

of the curve in Figure 5 and likewise the relation between solubility and 
pressure is indicated in Figure 6. 

Steinitzer 40 carried out experiments to determine the action of carbon 
dioxide when used for inflating pneumatic tires. He reported a decrease 

Stcinitzer, F. f Gummi-Ztg., 25, 1626-8. 



PHYSICAL PROPERTIES OF CARBON DIOXIDE 



49 



in the tensile strength of the sample and a tendency for it to become tacky. 
Yanmiamoto 47 also made solubility measurements of carbon dioxide in 
rubber. The specimens of tubing he used were cut into bits, dried and 
tested for increase in weight in carbon dioxide at a pressure of 1 atmos- 



IOW 

I6O 

140 

Q) 
J) 
tt l2 

O 
O 

O 100 

i. 

CL 

OL- 

Z 

ftl 

60 


O 



40 



































































































\ 


i 
























\ 
























\ 



























\ 


























v 
























H 


\ 
























X 


\ 
























S 


\ 
























> 


\ 


























X 


x 
























^s 


^ 


























^> 



















































-10 



60 



80 



110 



Temperature G. 



Fic.ukE 5. Effect of Temperature on Solubility of Carbon 
Dioxide in Rubber. 

(According to Vcnable and ftiwa) 

pherc and a temperature of 25 C. He found that black tubing (rf 4 25 = 0.93) 
dissolved 0.146 gram of carbon dioxide per 100 grams of rubber (equiva- 
lent to 68.8 cc. per 100 cc. at and 760 mm.) and bright brown tubing 

47 Yammamoto, T., Bull. Inst. I'hys. Research (Tokyo), 7, 999-1001 (1928). 



50 



CARBON DIOXIDE 



(rf 4 25 = 0.938) dissolved 0.166 gram of carbon dioxide per 100 grams of 
rubber (78.5 cc. per 100 cc. rubber). 

Relative diffusional rates of various gases through rubber have been 
determined by several investigators. In order to compare their results, 



r- 



I" 



7 



f 



i- 



/ 



FIGURE 6. 

Effect of Pressure on 
Solubility of Carbon Diox- 
ide in Rubber at 100 C. 

(According to 
Venable and Fuwa) 



o to to 30 +o so 

Cc. CO. ( N RT) pr IOO cc Rubber 



the reported data have been recalculated to a common basis and the results 
of these calculations are shown in Table 10. 

TABLE 10. Relative Rates of Diffusion of Various Gases Through Rubber. 

Observer 

Dewar .................. 

Alexjev and Matalskii 
Edwards and Pickering... 

Compressibility. Carbon dioxide deviates considerably from the 
ideal gas laws and especially is this true at the very high pressure under 
which it is often measured. Amagat's work on the compressibility of gases 
produced the most extensive and reliable data obtained to the present time. 
His values for the product PV covering a considerable temperature and 
pressure range are given in Table 11 and the plots of these values are 



N 2 
0.34 
43 


Air 
0.50 


A 
0.64 


He 
0.87 


2 
1.0 
1.0 


H a 
2.8 


CO, 
7.0 
6.0 


.35 


.71 


.57 


1.4 


1.0 


2.2 


6.4 



PHYSICAL PROPERTIES OF CARBON DIOXIDE 



51 



3 



rn ON vo l-x co -H c*5 VO IN* vo CM 



-J CM <M CM CM CM 



CO CO VO VO 

SCO VO T-H 
^H ,-H CM 



S^5 ^^ 
VO NO 

3j vo vo vq 



>< O 10 1> i-H CO ON VO 

2 CM ON oq oq oq oq ON 
-< o o co o o o 



I I 

Cj <=, Rj 



S E ^ 

12 ! 

^ -o ^ 






x 



a 

" 



g 



. H 



8 



voOiOOOOiO 

- 



500 

O ON t>N. 
O *>. vo 

* Tf VO 



cvi 






vo O C3 ^ O vo C5 vo O O vo 

"fcooNi-Hor>^t'rN icoco 

r i -H O co ON tx, vo "^ co ON 
i joico^-^vovotNjoqoNON 

OOOOOCOOOOOO 



ssgiggs 



<ocoooc>coocococoo 



<0 <0 _ _ _ 

vo o vp o vr 



VO CO *O 
T-I i i CM CM 



52 



CARKON DIOXIDE 



shown in Figure 7 and Figure 8. The latter isotherms have been plotted 
on an enlarged scale to show better the behavior of the gas at temperatures 
below the critical point. The dotted line AB represents the vapor-liquid 
curve and the values of P within this region represent the vapor pressure 
of the liquid phase. Perhaps one of the most interesting features of this 
plot is shown by the isotherms at 32 and 35 C. While they are above the 
critical temperature they show characteristics similar to those of the liquid- 
gas curve below this point. 




FIGURE 7. Compressibility Data of Amagat. 

The work of Keesom 4lS some years after that of Amagat also give an 
interesting series of isotherms. These isothennic values have been plotted 
in Figure 9. 

The compressibility of liquid carbon dioxide has been measured by 
Jenkin 40 and the results of his measurements are shown by the isotherms 
plotted in Figure 10. The ordinate of this graph represents the absolute 

Keesom, W. H., Verhandcl. Akad. Wctcnschafpen Amsterdam, 12, 391, 544, 616, 621 (1903); 
Communications Phys. Lab. Univ. Leiden, 88 (1903). 

"Jenkin, C. F., Proc. Roy. Soc. (London), A 98, 170 (1921). 



PHYSICAL PROPERTIES OF CARBON DIOXIDE 



53 



pressure in pounds per square inch. The curve AB is evidently the vapor- 
liquid limit curve for the system. 

There seems to he a paucity of information concerning the effect of 
pressure changes on the volume occupied hy solid carhon dioxide. Bridge- 
man has studied the effect of varying pressures on the melting point and 
his results will he considered in detail under that topic. 




Pressure in Atmospheres 

FIGURE 8. Compressibility Data of Amagat. 

The Coefficient of Thermal Expansion. Among the many reported 
values for the coefficient of expansion of carhon dioxide we find the fol- 
lowing : 

Reference 

Pogg. Ann., 55, 21 (1842). 
MPIII. Acad.. 26, 575 (1862^). 
Compt. rend.. 148, 1173 (1909). 
Arch. Set. Geneve, (3) 20, 5, 153, 
248 (1888). 



Temp. Range 
C. 

0-100 
0-100 
0-100 
0-100 


Coefficient of 
Expansion 

0.003691 
0.003710 
0.003724 
0.003724 


Observer 

Magnus 
Regnault 
Leduc 
Chappuis 



Average 



0.003712 



Dewar, Sir James, Proc. Roy. Inst., 21, 813-26; J. Chcm. Soc., 114, TI 186-7. Alcxjcv, D. and 
Matalskii, V., /. r/iim. fihys., 24, 737-41 (1927). Edwards, J. P. and Pickering, S. F., loc. cit. 



54 



CARBON DIOXIDE 



In some of the above cases the pressures under which the measurements 
were made were not stated. It may be assumed, however, that these values 
are for one atmosphere. Chappius has determined the coefficient of expan- 
sion at several different pressures with the following results : 



Pressure in mm. 

518 

998 

1377 



0to20C. 

0.0037128 
0.0037602 
0.0037972 



0to40C. 

0.0037100 
0.0037536 
0.0037906 



to 100 C. 

0.0037073 
0.0037410 
0.0037703 




FIGURE 9. 

Compressibility Data of 
Keesom. 



At higher pressure the values given by Amagat are very useful. They 
have been listed in Table 12. 

The Equation of State. One of the oldest and best known equations 
derived for the purpose of showing the relation between P, V and T in 
non-ideal gases is that of van der Waal. The usual form of this equation 
when applied to carbon dioxide takes the form 

. 001912). = n. 081518 T (7) 

where P is expressed in atmospheres, V in liters, T in degrees Kelvin 
/(f + 273.1) and n is the number of moles of gas taken. The values of 



PHYSICAL PROPERTIES OF CARBON DIOXIDE 55 

a : : i : : : :8 : :88 : 



3 






. 

_ i 
1 ~l 



00000000000 



. 

co . .10 . . . . i . .i-io-i-*t-r>i\o<f' > o*-iTt-voi- 

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o .1- .vo .ooo\ONe^sOrf-ro*oojrMCMri 

i s 

''' 



oo'oooooo'oo'oo 



T-^>.> 

_OOOOOOOOO*-i- 

8 o .op, o . o .P.o o .opo 

C> OOOOOOOOOOO 



^^000000000 

ppppppppppp 
ooooo'oo'oooo 



. 
O 



goooooddoooooooooooooo" 



o ^-- 

"'oopooooooooooooooopoop 
^oooooooooo'oo'ooooooo'ooo 



^ 
vo 



"J loooocjo 



... 
ooo'oooo^ooo 



w 

8 1 s 



rt i. 

~-r 2 vOOOCl^fOOeNjts.fi-iO\oOGOvo < ^-cocoe>j>icMr>|w-i 

^D 53 .j3Oo-i-"i-"cMc>aco-*f>i--oooooooooo 

ci a, iTpooopppppppopppppppppp 

*- g ^ooooo'oooo'o'oooo'ooooo'o'oo* 



I 
I 



I 



....... 

ooooooooo" oooooooooo 



cooooodoo'oo 



*** i-Ht>.*'CM-iT-io\tN.votoio'*i--rcorvicacvicMCM- 

-S:p 1 SSSpS8888888888888 

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56 



CARBON DIOXIDE 



a and b (.00719 and .001912 respectively) were calculated from the data 
of Amagat. Unfortunately this simple equation does not represent the 
actual relations between P, V and T over any considerable range of tem- 
perature and pressure. 

In an attempt to obtain an equation which more accurately represents 
the changes in condition of carbon dioxide Kammerlingh-Onnes r>0 modified 
the equation of van dcr Waals until it took the following form : 




.001912-- 



.00719 
.081507 7 



.... (8) 



FIGURE 10. 

Showing the Specific Volume 
of Carbon Dioxide at Various 
Temperatures and Pressures. 
The Compressibility Coefficient 
is the Slope of F.ach Isotherm. 



Pressure in pounds per sq. in. 

In this equation P f V , and T are expressed in the same units as in the old 
van der Waals' equation given above. 

Plank and Kuprianoff have derived an equation of state for calculating 
specific volumes of carbon dioxide which follows the experimental results 
quite well over a fairly wide pressure and temperature range. It also has 
the advantage of simplicity which is not a characteristic of most of these 
equations. The Plank and Kuprianoff equation is given in the following 
form : 

RT /0.0825 + 1.225 X 10' 7 P \ 

) <" 



(-)* 

\100/ 



60 Kammerlingh-Onnes, II., Communications Phys. Lab. Univ. Leiden, 118 b (1910). 



PHYSICAL PROPERTIES OF CARBON DIOXIDE 57 

The constants in this equation were computed when V was expressed in 
liters per kilogram, P in kilograms per square meter, T in degrees Kelvin 
and R had a value of 19.273. It will be observed that the expression 

70.0825 + 1. 225 XlO- 7 />\ 

\ /rvv / 



/_rv 
\ 100 / 



is a correction factor to the ideal gas equation PV = RT. When the above 
units are used this expression represents cubic meters per kilogram. 

Without doubt the most accurate of all equations of state yet proposed 
is that of Beattie and Bridgeman/' 1 This equation gives very accurate 
results for carbon dioxide over a temperature range from 252 C. to 400 
C. and a pressure range up to 200 atmospheres. It has the disadvantage 
that the evaluation of P or V is a very laborious operation. The equation 
is given in the following form : 

/?r(i e) A 

p = - - L (v - B ) .......... (10) 

v* if 

where A = A (l-a/v) ; 7? = /? (l-&A') ; and e = c/vT*. The constants 
for carbon dioxide when the specific volume is expressed in cc. per gram, 
T f + 273.13 and the pressure in atmospheres, are as follows: 

tf=1.865; /V=2.381; &= 1.6443; -4.=2586; a=1.621 and r=15.0xlO". 

These authors have compared pressures calculated with this equation with 
those observed by Amagat and found an average deviation of only 0.08 
per cent. 

Many other equations of state will be found in the literature but none 
of them has any very outstanding advantage over the ones given here. 

The Specific Volumes of Gaseous, Liquid and Solid Carbon Dioxide. 

While the volume occupied by a gram, kilogram or pound of carbon dioxide 
can readily be calculated from the data already given it is perhaps well 
to put these important values in a more usable form. The calculated 
results of Plank and KuprianofP 2 are excellent averages of the existing 
experimental data and cover pretty much the whole field. In Table 13 these 
values are listed for the liquid and vapor together with experimental data 
of Maass and Barnes for the solid state. 

The Triple Point. The existing data on the triple point of carbon 
dioxide are scanty but what we have are in such good agreement there can 

81 Beattie, J. A. and Bridtfeman, O. C., /. Am. Chcm. Soc. t 49, 1665-7 (1927). 
53 Plank, R. and Kuprianoff, J. t Loc. cit. 



58 



CARBON DIOXIDE 



TABLE 13. Specific Volume of Carbon Dioxide in the Gaseous, Liquid and Solid State. 



Temperature 


Saturated 
Vapor 


Saturated 
Liquid 


Solid 


C. 


F. 


Kelvin 


Liter 


Cu. ft. 


Liter 


Cu. ft. 


Liter 


Cu. ft. 


Kilogram 


Pound 


Kilogram 


Pound 


Kilogram 


Pound 


31 


87.8 


304.1 


2.156 


.03453 


2.156 


.03453 






30 


86.0 


303.1 


2.990 


.04789 


1.6768 


.02686 






25 


77.0 


298.1 


4.167 


.06675 


1.4108 


.02269 






20 


68.0 


293.1 


5.258 


.08422 


1.2976 


.02078 






15 


59.0 


288.1 


6.329 


.10138 


1.2226 


.01958 






10 


50.0 


283.1 


7.519 


.12044 


1.1655 


.01867 






5 


41.0 


278.1 


8.850 


.14176 


1.1197 


.01793 









32.0 


273.1 


10.383 


.16632 


1.0813 


.01732 






- 5 


23.0 


268.1 


12.141 


.19448 


1.048 


.01678 






-10 


14.0 


263.1 


14.194 


.22792 


1.019 


.01632 






-15 


5.0 


258.1 


16.609 


.26606 


0.994 


.01592 






-20 


- 4.0 


253.1 


19.466 


.31188 


0.971 


.01555 






-25 


-13.0 


248.1 


22.885 


.36659 


0.950 


.01521 






-30 


-22.0 


243.1 


27.001 


.43251 


0.931 


.01491 






-35 


-31.0 


238.1 


32.008 


.51272 


0.913 


.01402 






-40 


-40.0 


233.1 


38.164 


.61132 


0.897 


.01437 






-45 


-49.0 


228.1 


45.809 


.73378 


0.881 


.01411 






-50 


-58.0 


223.1 


55.407 


.88752 


0.867 


.01388 






-55 


-67.0 


218.1 


67.620 


1.0832 


0.853 


.01366 






-56.6 


-69.0 


216.5 


72.220 


1.1568 


0.849 


.01360 


0.661 


.01059 


-60 


-76.0 


213.1 






0.840 


.01345 


0.657 


.01052 


-65 


-85.0 


208.1 










0.652 


.01044 


-70 


-94.0 


203.1 










0.647 


.01036 


-75 


-103.0 


198.1 










0.643 


.01030 


-80 


-112.0 


193.1 










0.639 


.01023 


-85 


-121.0 


188.1 










0.635 


.01017 


-90 


-130.0 


183.1 










0.632 


.01012 


-95 


-139.0 


178.1 










0.629 


.01007 


-100 


-148.0 


173.1 










0.627 


.01004 


-110 


-166.0 


163.1 










0.623 


.00998 


-120 


-184.0 


153.1 










0.619 


.00992 


-130 


-202.0 


143.1 










0.615 


.00985 


-183 


-297.4 


90.1 










0.599 


.00960 



be but little doubt as to the value of this constant. The results obtained by 
four investigations are as follows : 



Triple 
Point 

-56.7 

- 56.24 
-56.4 

- 56.59 



Vapor 

Pressure 

Atmosphere 

5.1 
5.10 
5.11 
5.113 



Observer 

Villard and Jarry 
Kuenen and Robson 
Zeleny and Smith 
Meyers and Van Dusen 



Reference 

Comfit, rend., 120, 1413 (1895). 
Phil. Mag. (6) 3,622 (1902). 
Phys.Rcv. (1) 24,42 (1907). 
Refrigerating Eng. 13, 180 (1926). 



PHYSICAL PROPERTIES OP CARBON DIOXIDE 



59 



Plank and Kuprianoff consider that - 56.6 is the most reliable temperature 
value and this will be considered the triple point in all future calculations 
in this work. 

The Critical Temperature. The critical temperature is often defined 
as that temperature above which a substance cannot exist in the liquid 
state (however, cf. page 60). At this temperature the value of the sur- 
face tension becomes zero and the densities of the liquid and its satu- 
rated vapor become equal. At the critical temperature there exists a com- 
plete mutual solubility of the liquid and the gas. The usual visual evidence 
of this change is the disappearence of the meniscus at the surface of the 
liquid. That this is not a clear cut point has been demonstrated by several 
researches. It is not surprising, therefore, that critical temperature meas- 
urements by different investigators do not always agree. Meyers and 
Van Dusea have collected and tabulated the data obtained by a large number 
of investigators. These values are given in Table 14. 

TABLE 14. The Critical Temperature and Critical Pressure of Carbon Dioxide. 

Reference 

Trans. Roy. Soc. (London), 159, II 575 

(1869). 
Compt. rend. 92, 840 (1881). 

Phil. Mag. 18, 210 (1884). 

Compt. rend., 114, 1093, 1322 (1892). 

Compt. rend.. 118, 976 (1894). 

/. I'liys. (3) 441 (1894). 

Verhandcl Akad. Wetenschappcn Amster- 
dam, 94 (1896) ; Communications Ph\s. 
Lab. Univ. Leiden, 28. 

Phil. Mag., (5) 44, 179 (1897). 

n\iU. acad. roy. Bclqique, 31, 147, 379 (18%). 

Verhandcl dent, physik. Gcs., 5, 238 (1903). 

Verhandel Akad. Amst. 321, 533, 616 (1903). 

Brinkmann Dissertation Amsterdam (1904). 

Verhandel Akad. Amst. 44 (1907) ; Com- 
munications Phys. Lab. Univ. Leiden. 98, 
(1907). 

Phys. Rev. 23, 470 (1908). 



30.92 
31.0 

31.9 

31.35 

31.40 

31.7 

31.0 



P e Atmos. 
73 



77 
72.9 



Observer 
Andrews 

Hautefeuille and 

Cailletet 
Dewar 
Ainagat 
Chappuis 
Villard 
Vcrschaffelt 



31.1 73.26 
31.4 
30.95 to 31. 7 
30.98 72.93 
31.12 
30.985 


Kuenen 
DC Keen 
Von Wesendonck 
Keesom 
Brinkmann 
Onncs and Fabius 



31.26 

31.10 
31.00 
30.97 
31.1 

30.96 



73.00 
72.85 

72.95 



Bradley, Brown 

and Hale 
Dorsman 
Cardoso and Bell 
Hein 
Meyers and 

Van Duscn 
Kennedy 



Dorsman Dissertation Amsterdam (1908). 
J.chim.phys. 10,500 (1912). 
Z. physik. Chcm. 86, 385 (1913-14). 
Refrigerating Eng. 13, 180 (1926). 

J. Am. Chcm. Soc. 51, 1360 (1929). 



The most probable value for the critical temperature is 31.0 C. and for 
the critical pressure 72.80 atmospheres. 53 

The work of Bradley, Brown and Hale 54 has given us some interesting 
information on the effect of mechanical vibration on liquid carbon dioxide 

M Meyers, C. H. and Van Dusen, M. S., Bur. Standards J. Research, 10, 381-412 (1933). 
"Bradley, W. P., Brown, A. W. and Hale, C. F., Phy*. Rev., 26, 470-82 (1908); ibid.. 27, 
90-106 (1909). 



60 CARBON DIOXIDE 

near the critical temperature. When the liquid is within two degrees of 
its critical temperature it is exceptionally sensitive to a minute change in 
volume so that the vibrations produced by a tuning fork, under the proper 
conditions, arc sufficient to give rise to the so-called fog effect. These 
investigators have also found evidence that liquid carbon dioxide can exist 
above the critical temperature. An excellent discussion of the critical state 
of carbon dioxide has been made by IIein. r>r> 

Melting Point. Below the triple point (-56.6 C.) solid carbon 
dioxide sublimes directly to a gas. The sublimation temperature is of 
course a function of the opposing pressure and at one atmosphere pressure 
the temperature of sublimation is -78.515 C. (-109.33 R). no This 
temperature is so easily reached with solid carbon dioxide that it is often 
used as a reference point for standardization of low temperature thermom- 
eters. Temperatures below this point or even up to the triple point can 
easily be maintained by controlling the pressure of the gas above the solid 
carbon dioxide. With a vacuum produced by an ordinary water aspirator 
it is possible to reach temperatures well below 100 C. The relation 
between temperature and pressure can be determined by reference to the 
vapor pressure table of the solid. 

The effect of pressure changes on the melting point of solid carbon 
dioxide was studied by Kuencn and Robsoir"' 7 who calculated that dp/dl 
was equal to 47.9 atmospheres per degree centigrade while Tammann 158 
obtained a value of 50 atmospheres per degree. Rridgemaiv very definitely 
located the freezing temperatures at pressures up as high as 11613 atmos- 
pheres. His results are shown in Table 15. The most interesting fact 
brought out by this table is that carbon dioxide can exist as a solid at tem- 
peratures above its critical point. 

TABLE 15. Showing the Freezing Points of Carbon Dioxide at Various Pressures. 

(Data by Bridgeman) 

f Pressure > Temperature Change in vol. AV 

Kg/cm. 8 Atmos. C. Cm.Ygm. 

1 5.11 -56.6 0.188 

1000 967.8 37.3 

2000 1935.5 -20.5 

3000 2903.2 - 5.5 .1071 

4000 3871.1 + 8.5 .0979 

5000 4838.7 21.4 .0896 

6000 5806.6 33.1 .0822 

7000 6774.3 44.2 .0755 

8000 7742.1 55.2 .0697 

9000 8709.8 65.8 .0644 

10000 9677.7 75.4 .0602 

11000 10645.5 84.6 .0564 

12000 11613.0 93.5 .0531 

M Hein. Paul, Z. phyrik. Clicm., 86, 385-426 (1913-14). 

M Meyers, C. H., and Van Dusen, M. S., Loc. cit. 

"Kuencn, J. P., and Rohson, W. G. f Phil. Maq., (6) 3, r,22 (1902). 

M Tammann, G., Wicd. Ann., 68, 572 (1899). 

Briclgeman, P. W., Phys. Rev. (2) 3, 158 (1914). 



PHYSICAL PROPERTIES OP CARBON DIOXIDE 61 

The decrease in volume as carbon dioxide changes from the liquid to 
the solid state is exceptionally large. The specific volume of the liquid, 
at the triple point, is 0.849, while for the solid it is 0.661 liters per kilogram. 
This decrease amounts to 28.5 per cent while water increases about 10 per 
cent on changing to the solid condition. It will be noticed that at higher 
temperatures this volume change on freezing becomes much less. 

Vapor Pressure of Liquid Carbon Dioxide. Various parts of the 
liquid-vapor equilibrium curve have been studied by such investigators as 
Kegnault, Caillctet, Amagat and Villard. The recent measurements of 
Meyers and Van Dusen, however, have covered the whole field from the 
triple point to the critical temperature. This work was so carefully and 
completely done that it inspires considerable confidence in the reliability of 
the results. The values obtained in this investigation are shown in Tables 
16 and 17. 

Plank and Kuprianoff found that Young's equation 



/ T V 
= a( b } 

VlOO / 



(ID 



fitted the vapor pressure curve of Meyers and Van Dusen very well. When 
p is expressed in kilograms per square centimeter the values for the con- 
stants are: a = 7.856, 6 = 1.261, //-= 3.917. 

Bridgeman (JO measured the vapor pressure of carbon dioxide at the 
water ice point with the view of obtaining a pressure system for the calibra- 
tion of piston gages which would be less complicated than the mecury 
column. His value at C. was 34.4009^0.0013 atmospheres (# = 980.665) 
or 26144.7 =*= 1.0 international mm. of mercury. 

Vapor Pressure of Solid Carbon Dioxide. In order to determine the 
course of the equilibrium curve for the system CO 2(A{ ) ^ COai//) it is 
necessary to piece together the results of several research workers in this 
field. At very low temperatures, mcasurcMiients have been made by Kam- 
merlingh Onncs and Weber" 1 who obtained the following results: 

Temp C -183 -179.6 -175.37 -171.01 -168.83 -167.04 

Pressure mm 000006 .0000195 .0000795 .000303 .000593 .000983 

At 134 C. the vapor pressure of solid carbon dioxide is only slightly 
over 1 mm. and from this point up to the triple point, data is available for 
plotting the equilibrium curve with considerable accuracy. However, the 
course of this curve can perhaps be calculated better by using the empirical 
equation developed by Plank and Kuprianoff. This equation may be 
written 

2206.455 
k>g/=58.361 21 .431 log r-f 0.02527 T (12) 

80 Bridgeman, (). C. t /. Am. Chcm. Soc., 49, 1174-83 (1927). 

Bl KammerlitiKh Onnes, IT., ami Weber, S., Verhandcl. Akad. W ctcnschappen Amsterdam, 22, 
226-39. 



62 



CARBON DIOXIDE 




?1 3^ 

i"?e>c 



& 



vOCOi-HVpOOOCMOO 

to i LO o i ir-irxt^ 

vo -* rf t> O ON vO 

iOOO-iiOi-iCMQ'- 

T-H r-i CM CO Tf 10 



COV 



CM 

CO OO *~H -H ^5 r-H 

OO r ~^ VO *O ^5 *O 

S \o S ,-; S o 

rH i-l CM CO ^ 10 





c\j^ 

OO *^ 

^>^^o\oo 

H i CM CM CO 




N 28S 




co^ 



_ ^H -H CM CM CO rt 

i I 

^ovocxir^"S 




10 i<cooyp^ 
5 not 



.CMCMCMfOOfM 



O^.t 



PHYSICAL PROPERTIES OF CARBON DIOXIDE 



63 



Values obtained by means of this equation are shown in Table 18 together 
with data taken from the works of the various authors indicated. 

TABLE 18. Vapor Pressure of Solid Carbon Dioxide in mm. of Mercury. 

Meyers Kuenen Henning Plank 

t T and and and v. Siemens K.Onnes and 

C. Van Dusen Robson Stock Kuprianoff 



56.6 
60 
65 
70 
75 

78.52 

80.05 

87.91 

95.92 

102.96 

109.74 

117.78 

127.21 

134.68 



216.5 

213.1 

208.1 

203.1 

189.1 

194.58 

193.05 

185.19 

177.18 

170.14 

163.36 

155.32 

145.89 

138.42 



3385.7 



30172 

2107.8 

1428.8 

972.8 



760 

G69.9 

338.5 

158.7 

76.7 

35.7 



Refci cnces 



13.09 
3.50 



1.073 



3884.0 Tr. Pt. 
3076.7 
2157.4 
1489.1 
1010.1 
760 
669.5 
338.0 
158.3 
76.5 
35.7 
13.18 
3.52 
1.073 



Meyers and Van Dmen, Rcfriacratinn Hnfj., 13, 180 (1926). 
Kuenen, J. P. and Robson, W. ('.., Phil. Man. (6), 3, 149 (1902). 
Henning, F. and Stork, A., Z. Pliysik., 4, 22f, (1921). 
v. Siemens, H., Dissertation Brrlin and Ann. Phy*. (4) 42, 871 (1913). 

Kammerlingh Onnes, H. and Weber. S., Communications 1'hys. Lab. Univ. Leiden. 137 b and c 
(1913). 




Temperature "O 

FIGURE 11. Equilibrium Curve for Carbon Dioxide. 

The Equilibrium Diagram of Carbon Dioxide. The triple point dia- 
gram for carbon dioxide has been plotted in Figure 11. 

Dissociation of Carbon Dioxide at High Temperatures. The degree 
of dissociation of carbon dioxide at elevated temperatures was first calcu- 



64 CARBON DIOXIDE 

lated by Lowenstein 02 from data obtained by the Victor Meyer-Nernst 
method of determining vapor pressures. At 1550 C. he calculated the 
per cent dissociation to be 0.4. Somewhat later Bjerrum 03 by means of the 
equation 

=2RTK C ............ (13) 



where a = degree of dissociation and K c is the dissociation constant, calcu- 
lated the per cent dissociation of carbon dioxide over a wide range of 
temperatures and pressures. The results obtained by these calculations are 
shown in table 19. 

TABLE 19. Per Cent Dissociation of Carbon Dioxide at Various 
Temperatures ami Pressures. 

(Calculated by Rjerrum) 

Temp. f - Pressure - \ 
K .1 atmos. 1 atmos. 10 atmos. 100 atmos. 

1000 .0000531 .0000247 .0000114 .00000531 

1500 .104 .0483 .0224 .0104 

2000 4.35 2.05 .960 .445 

2500 33.5 17.6 8.63 4.09 

3000 77.1 54.8 32.2 16.9 

3500 93.7 83.2 63.4 39.8 

4000 97.9 93.9 83.4 63.8 

4500 99.2 97.4 92.4 80.3 

5000 99.6 98.7 96.1 89.0 

The Molecular Heat Capacity of Gaseous Carbon Dioxide. It is 

rather difficult to obtain from the literature, specific or molal heat data on 
carbon dioxide in which one may have absolute confidence. Many inves- 
tigators have measured the specific heat of this compound and many others 
have calculated it, using mathematical expressions based on experimental 
results obtained by other workers. The earlier investigators often failed 
to specify the temperature under which their measurements were made. 
Others determined the ratio of specific heats of carbon dioxide at two 
different temperatures and some determined the ratio of the specific heat 
of carbon dioxide to the specific heat of some other gas at the same temper- 
ature. A very complete list of all these investigators is given by Mellor 04 
and only the more recent work will be considered here. 

For many years the most popular equation for calculating specific or 
molal heats has been that of Lewis and Randall 05 which is usually written 
for carbon dioxide in the following form : 

C P =7.0+0.0071T- 0.00000186 r .......... (14) 

This equation is based on the experimental values of Holhorn and Austin, 00 

M Lfiwcnstein, Leo, Z. physik. Chcm., 54, 707 (1906). 
"Bjerrum, Niels, Z. physik. Chcm.. 79, 537-550 (1912). 

64 Mellor, J. W., "Comprehensive Treatise on Inorganic and Theoretical Chemistry," 6, page 
34, Longmans, Green and Co. (London). 

Lewis, G. N., and Randall, M., /. Am. C7irw. Soc., 34, 1128 (1912). 

68 Holhorn, L., and Austin, L., Abhandl. physik. tech. Rcichsanstalt, 4, 131 (1905). 



PHYSICAL PROPERTIES OF CARBON DIOXIDE 



65 



Holborn and Henning, 07 and Pier. 08 Recent determinations seem to indi- 
cate that this equation gives values much too high especially at elevated tem- 
peratures. Leduc 09 has made a critical survey of the literature and has 
selected certain values for the molal heat capacity for carbon dioxide which 
he considers somewhat more reliable than those previously published. That 
Leduc was justified in his choice of values seems evident from the curves 




Temperature ' 

FIGURE 12. Experimental Data on the Molal Heat Capacity of Carbon 
Dioxide by Various Investigators. 

Curve I by Eucken and Liide Experimental 

Curve TI by Holborn and Henning Experimental 

Curve III by Lewis and Randall Calculated 

Curve IV by Leduc Calculated 

Curve V by King and Partington Experimental 

Curve VI by Chopin Experimental 

plotted in Figure 12. The curve plotted by means of the Lewis and Randall 
equation agrees fairly well with that made from the experimental values 
of Holborn and Henning but the curve obtained with Leduc's values does 
not agree with either of them. This latter plot is supported to a certain 
extent by the recent experiments of Chopin 70 and those made by King and 

67 Ilolborn, L., and Henning, F. f Ann. Physik., 23, 809-45 (1907). 

8 Pier, M. f Z. Elector ochcm., 15, 536 (1909); 15, 897 (1910). 

w Leduc, A., "International Critical Tables," 5, 83, McGraw-Hill Book Co., New York (1929). 

70 Chopin, Marcel, Compt. rend., 188, 1660-2 (1929). 



66 



CARBON DIOXIDE 



Partington. 71 The results obtained by Eucken and Liide 72 are hard to 
explain as they do not support any of the investigators just mentioned. 

Table 20 has been constructed using Leduc's values above C. and 
values calculated from the equation 

C P =8.68+. 0066 /-. 0000022 1* (15) 

TABLE 2Q.The Molal Heat Capacity of Carbon Dioxide in Gram. Cal. 

't \ CV > ^ g &0--I 

- 80 -112 6.085 8.166 8.176 1.342 

- 70 - 94 6.150 8.229 1.338 
60 76 6.216 8.292 8.280 1.334 

- 50 - 58 6.282 8.355 1.330 

- 40 - 40 6.349 8.419 8.397 1.326 

- 30 - 22 6.417 8.484 1.322 

- 20 - 4 6.485 8.548 8.506 1.318 

- 10 +14 6.555 8.614 1.314 

32 6.625 8.680 8.612 1.310 8.680 

+ 100 212 7.197 9.220 1.281 8.927 

200 392 7.656 9.670 9.585 1.263 9.138 

300 572 8.081 10.077 1.247 9.338 

400 752 8.476 10.468 10.402 1.235 9.537 

500 932 8.822 10.808 1.225 9.737 

600 1112 9.146 11.133 11.082 1.217 9.897 

700 1292 9.449 11.433 1.210 10.098 

800 1472 9.724 11.708 11.644 1.204 10.268 

900 1652 9.956 11.947 1.200 10.437 

1000 1832 10.173 12.157 12.106 1.195 10.569 

1100 2012 10.357 12.346 1.192 10.698 

1200 2192 10.528 12.518 12.488 1.189 10.808 

1300 2372 10.680 12.666 1.186 10.925 

1400 2552 10.817 12.807 12.810 1.184 11.047 

1500 2732 10.964 12.949 1.181 11.168 

1600 2912 11.092 13.077 13.088 1.179 11.277 

1700 3092 11.220 13.206 1.177 11.407 

1800 3272 11.351 13.338 13.347 1.175 11.527 

1900 3452 11.472 13.457 1.173 11.648 

2000 3632 11.612 13.598 13.597 1.171 11.768 

below C. The ratios of C p to C v below C. were mechanically extra- 
polated from those given by Leduc above this temperature. It is believed 
that this extrapolation can be made with considerable confidence as it 
extends the curve only a relatively short distance. The molal heats at con- 
stant volume (C v ) were calculated from C p by means of the ratio of these 
two values. 

The whole range of values for C p from 80 to 2000 C. may be calcu- 
lated by means of the equation 

Cp=7.0+6.56x 10 J 7- 2.503 Xl0-'r +3.932 xlO- lo r (16) 

with an accuracy well within one per cent at any point. Many other empiri- 
cal equations have been derived for the calculation of specific or molal 

King, F. E., and Partington, J. R., Phil. Matj. t (7) 9, 1020-6 (1930). 

Eucken, A., and v. Liide, K. f Z. physik. Chem., Abt. B 5, 413-41 (1929). 



PHYSICAL PROPERTIES OF CARBON DIOXIDE 



67 



heats of carbon dioxide and most of them take the same general form, i. e., 
C p =a+bt-ct 2 + dt' A in which a, b, c and d are constants. The value of 
these constants vary considerably with different investigators. 




Temperature "C 



FIGURE 13. Molal Heat Capacity of Carbon Dioxide at Different 
Pressures and Temperatures. 

That the specific heat of carbon dioxide changes with a change in pres- 
sure has been demonstrated by Jcnkin and Pye 73 who have determined the 
heat capacities at a number of different temperatures and pressures. The 

TABLE 21. The Molal Heat Capacity of Carbon Dioxide in Gram 

Cal. at Various Pressures and Temperatures. 

(Data from Jenkin and Pye.) 



Pressure 




Atmos. 


10.2 


lbs./sq. in. 


150 


Tempera- 




ture C. 




-30 


10.186 


-25 


10.186 


-20 


10.186 


-15 


10.186 


-10 


10.186 


- 5 


10.186 





10.186 


+ 5 


10.186 


+ 10 


10.186 


+ 15 


10.186 


+20 


10.186 


+25 


10.186 


+30 


10.186 



13.6 
200 



11.88 
11.70 
11.53 
11.35 
11.13 
11.00 
10.82 
10.65 
10.47 
10.30 
10.12 
9.94 
9.72 



20.4 
300 



12.85 
12.63 
12.41 
12.19 
11.97 
11.75 
11.48 
11.26 
11.04 
10.82 



27.2 
400 



34.0 
500 



40.8 
600 



47.6 
700 



15.05 
14.52 
14.04 
13.55 
13.02 
12.54 
12.06 
11.57 



17.42 
16.72 
16.02 
15.27 
14.52 
13.81 
13.11 



19.80 

18.52 24.07 

17.25 21.56 

15.97 19.10 

14.70 16.63 



"Jenkin, C. F., and Pye, D. R. f Phil. Trans.. A 215, 353 (1915). 



68 CARBON DIOXIDE 

results of their measurements are plotted in Figure 13. The curve repre- 
senting the pressure of 1 atmosphere was based on the values of Ledtic and 
this, with the other curves, shows very clearly how the slope changes with a 
change in pressure. The data from which these plots were made are given 
in Table 21. 

The Molal Heat Capacity of Liquid Carbon Dioxide. Jenkin and 
Pye 74 have determined the specific heats of liquid carbon dioxide from 
-50 to +20 C. Their results are as follows: 

t, C -50 -40 -30 -20 -10 10 20 

Sp. ht. (c p ) 47 .49 .515 .54 .57 .60 .64 .68 

Mol. ht. (C P ) 20.7 21.6 22.7 23.5 25.1 26.4 28.2 29.9 

No other experimental determinations have been made in recent years, but 
Keyes and Kinney 75 have calculated the probable specific heat of the liquid 
as 0.543 at temperatures between and -20 C. and 0.544 at -40 C. 

The Molal Heat Capacity of Solid Carbon Dioxide. Without doubt 
the best experimental values for the molal heat capacity of solid carbon 
dioxide has been furnished by Maass and Barnes 70 who obtained an average 
of 12.496 gram cal. per gram mole between 115 and 183.1 C. The 
molal heat capacity of the solid between 56 and 110 C. can be calcu- 
lated by means of the equation 

Cp=44 (0.400- 0.00283 r +0.00001 25 r) (17) 

Some of the values calculated from this equation expressed as gram cal. 
per gram mole are: 

t, C -56.6 -60 -70 -80 -90 -100 -110 

C P 16.41 16.06 15.00 14.08 1324 12.54 11.92 

The Latent Heat of Vaporization of Carbon Dioxide. The first mea- 
surement of the latent heat of vaporization of carbon dioxide was made by 
Rcgnault. 77 At 17 C. he obtained 40.0 cal. per gram. Somewhat later 
Chappuis 78 found a value of 56.25 cal. per gram at C. Mathias 79 by 
means of a few direct measurements obtained 

Temp. C 12.35 22.04 29.85 30.82 

Lv in gram cal./gram 44.94 31.8 14.4 3.72 

Indirect calorimetric determinations have been made by Jenkin and 
Pye between +20 and 30 C. and several investigators have published 
values calculated in various ways. No important direct measurements 
have been made below 0. 

Jenkin, C. F., and Pye, D. R., Phil. Trans., A 213, 67-117 (1914). 

"Keyes, F. G., and Kinney, A. W., Refrigerating Eng., 3, Part 4, Jan. (1917). 

TO Maass, O., and Barnes, Proc. Roy. Soc. (London), A 111, 224-44 (1926). 

" Regnault, H. V., Mtm. acad., 26, 335 (1862). 

"Chappuis, J., Ann. chim. phys., (6) 15, 517 (1888). 

"Mathias, E., Diss. Paris, No. 6807 (1890). 



PHYSICAL PROPERTIES OF CARBON DIOXIDE 



69 



Plank and Kuprianoff have tabulated the most important experimental 
and calculated values for the latent heat of vaporization between the critical 
point and the triple point. These values may be calculated, with an accuracy 
which is sufficient for practically all purposes, by means of the equation of 
Thiesen, 80 

/.t>=15.2(304.1-r)- :{R ............ (18) 

TABLE 22. Heat of Vaporisation of CO z Lv in Cm. Cal/Gm. 



Mollicr 



+31.0 


+87.8 


0.000 


30.0 


86.0 


14.93 


25.0 


77.0 


28.84 


20.0 


68.0 


36.75 


15.0 


59.0 


42.69 


10.0 


50.0 


47.52 


5.0 


41.0 


51.67 


0.0 


32.0 


55.19 


- 5.0 


23.0 


58.36 


-10.0 


14.0 


61.18 


-15.0 


5.0 


63.73 


-20.0 


4.0 


66.04 


-25.0 


-13.0 


68.15 


-30.0 


-22.0 


70.07 


-35.0 


-31.0 




-40.0 


-40.0 




-45.0 


-49.0 




-50.0 


-58.0 




-55.0 


-67.0 




-56.6 


-69.9 





Langen 


Eichel- 
berg 


Jcnkin 
and 
Pye 


Tijr Plank and 
Keyes Kuprianoff 


0.00 


0.00 






0.00 


15.34 


14.7 




19.77 


15.05 


28.74 


28.4 






28.53 


36.20 


36.5 


36.5 


38.61 


37.10 


42.12 


42.5 


41.9 




43.07 


47.05 


47.5 


46.2 


48.50 


48.09 


5128 


52.2 


50.3 




52.35 


55.03 


55.8 


54.1 


56.15 


56.13 


58.42 


59.2 


57.7 




59.50 


61.54 


62.4 


60.9 


62.67 


62.51 


64.45 


65.2 


63.8 




65.26 


67.20 


67.8 


66.5 


68.45 


67.79 


69.82 


70.5 


69.0 




70.14 


72.32 


72.9 


71.3 


73.72 


72.37 


74.76 


75.1 


73.6 




74.51 


77.16 


77.4 


75.7 


78.59 


76.58 


79.52 


79.7 


77.8 




78.59 


81.88 


81.8 


79.9 


83.16 


80.56 




83.9 






82.50 










83.12 



B. t. u. 
per 
Ib. 
0.00 
27.09 
51.35 
66.78 
77.53 
86.56 
94.23 
101.03 
107.10 
112.52 
117.47 
122.02 
126.25 
13027 
134.12 
137.84 
141.4ft 
145.01 
148.50 
149.62 

Table 22 gives the results of the tabulation of Plank and Kuprianoff. 

Heat of Sublimation of Carbon Dioxide. The latent heat of sublima- 
tion of carbon dioxide was first determined by Favre 81 who obtained a 
value of 138.7 gram cal. per gram at a pressure not stated but probably 
atmospheric. Bchn 82 some years later found a value of 142.4 gram cal. per 
gram at 78 and 1 atmos. pressure. Kuenen and Robson by means of 
the Clausius-Clapeyron equation calculated a value of 129.9 gram cal. per 
gram at the triple point. Recently Andrews 83 obtained at atmospheric 
pressure 141.0 and Maass and Barnes 84 136.9 gram cal. per gram. At 
lower temperatures and pressures we have the measurements of Eucken and 
Donath 85 who found 140.7 at -103.1 C. and 144.0 gram cal. per gram at 
-133.1 C. 

The most recent calculations have been made by Plank and Kuprianoff 
who, by means of a modified form of the Clausius-Clapeyron equation, 
have computed a series of values which are in good agreement with experi- 

80 Thiesen, Vcrhandel Phys. Ges. Berlin, 16, 80 (1897). 

"Favre, P. A., Compt. rend., 39, 729 (1854); Licbig's Ann., 92, 194 (1854). 

M Bchn, U., Ann. Physik., (4) 3, 733 (1900). 

"Andrews, J. W M /. Am. Chcm. Soc., 47, 1597 (1925). 

84 Maasa, O. f and Barnes, Proc. Roy. Soc. (London), A 111, 224 (1926). 

88 Eucken. A., and Donath, E. f Z. physik. Chcm., 124, 194 (1926). 




70 CARBON DIOXIDE 

mental results. The equation they used is somewhat complicated and is 
difficult to use unless one has access to their table of correction factors. 
A much more usable equation for calculating heats of sublimation is 

L 8 =L - 0.2409 T+0.0014957 7" J - 0.00000431 T (19) 

where L is a constant which can be calculated from any experimental data. 
Plank and Kuprianoff used for L a value of 158.96 which was calculated 
from the experimental data of Eucken and Donath. 

The calculated data of Plank and Kuprianoff are given in Table 23. 

TABLE 23. Heat of Sublimation La of Carbon Dioxide in Gram. CaL/Gram. 

and B.t.u./lb. 

L* 

C. F. Atmos. ^-^' 

g. 

- 56.6 - 69.9 5.112 129.88 233.78 

- 60.0 ~ 76.0 4.048 131.35 236.43 

- 65.0 ~ 85.0 2.838 133.38 240.08 

- 70.0 - 94.0 1.959 134.93 242.87 

- 75.0 -103.0 1.329 136.13 245.07 

78.9 110.0 0.986 136.89 246.40 

- 80.0 112.0 0.885 137.08 246.74 

- 85.0 -121.0 0.577 137.88 248.18 

- 90.0 130.0 0.367 138.57 249.43 

95.0 139.0 0.228 139.19 250.54 
-100.0 -148.0 0.137 139.77 251.59 

Heat of Fusion of Carbon Dioxide. It is evident that the heat of 
fusion L f of carbon dioxide is equal to the heat of sublimation L minus the 
heat of vaporization L v . From the numerical values already given for these 
at the triple point we find 

Lf=LsLv=l29 .88 83.12=46.76 gram cal. per gram. 

Maass and Barnes have measured the heat of fusion at the triple point and 
found 45.3 gram cal. per gram. Kuenen and Robson also obtained 43.8 for 

TABLE 24. Heat of Fusion Lf of Carbon Dioxide in gram. cal. /gram and B.t.u./lb. 
(Data from P. W. Bridgeman) 

Lf Lf 

' ' P gm. cal. B.t.u. 

C. F. Atmos. - 

gm. lb. 

-56.6 - 69.9 5.11 46.7* 84.06* 

- 5.5 + 22.1 2903.2 46.7 84.06 

+ 8.5 + 47.3 3871.1 48.6 87.48 

+21.4 + 70.5 4838.7 50.1 90.18 

+33.1 + 91.6 5806.6 51.0 91.80 

+44.2 +111.6 6774.3 51.0 91.80 

+55.2 +131.4 7742.1 51.2 92.16 

+65.8 +150.5 8709.8 51.3 92.34 

+75.4 +167.7 9677.7 51.7 93.06 

+84.6 +184.2 10645.5 52.2 93.96 

+93.2 +199.8 11613.0 52.8 95.04 

* From Plank and Kuprianoff. 



PHYSICAL PROPERTIES OF CARBON DIOXIDE 71 

this value. The values of L/ at different temperatures and pressures have 
been determined by Bridgeman 80 and his results are given in Table 24. 

The Enthalpy of Carbon Dioxide. When a fluid is permitted to pass 
adiabatically through a small orifice or a porous plug in such a manner that 
its kinetic energy of flow on either side of the opening is too small to be of 
consequence then 

!+ p 1 v l =u 2 + p z v 2 or tt-f />v=a constant ........ (20) 



where MI and u are the specific intrinsic energies, v\. and V2 are the corre- 
sponding specific volumes at the respective pressures pi and p% before and 
after passing through the opening. The function (u+pv) is known as the 
enthalpy of the fluid. In the following discussion we will designate this 
function as i. 

Under isenthalpic conditions or with a constant enthalpic porous plug 
expansion, changes in both temjxiraturc and volume usually accompany the 
pressure drop across the plug. The limiting ratio of the temperature 
change A/ to the pressure change A/> as the latter approaches zero is vari- 
ously known as the Joule-Thompson effect, the Joule-Kelvin effect or the 
throttling effect. This ratio designated by ft, is analytically defined by the 
relation 

(21) 



Kester 87 was perhaps the first to make any attempt to conduct throttling 
experiments on carbon dioxide over a wide pressure range. He applied 
his measurements to the equation 



. (22) 

OH 



ill which a and b are constants. 

Jenkin and Pyc ss conducted an extensive series of throttling experi- 
ments with liquid carbon dioxide over a temperature range between +15 
and 55 C. The most interesting part of this work was the establish- 
ment of an inversion point at 25 C. Below this temperature the liquid 
is slightly heated after passing through a small orifice. The enthalpy of 
the liquid was also studied at 50 and 63 atmos. pressure and between 39 
and + 10 C. A little later another series of measurements was made by 
the same investigators 89 in which the research range was greatly extended. 
This work gave values for the enthalpy of the vapor from 10.5 to 50 atmos. 
pressure and for temperatures from 30 C. to the critical point. The 
liquid values were found between 33 and 50 C. while the superheated 
vapor was studied from 21 to 50 atmos. pressure and between +12 and 
+ 30 C. 

86 Bridgeman, P. W., Phys. Rev., (2) 3, 158 (1914). 

"Kcstcr, F. E., Physik. Z., 6, 44 (1905); Phys. Rev., (1) 21, 260 (1905). 

m Jenkin, C. F., ami Pyc, D. R., Trans. Roy. Soc. (London), A 213v 67 (1914). 

w jcnkin, C. F., and Pye, D. R., Trans. Roy. Soc. (London), A 213, 353 (1915). 



72 



CARBON DIOXIDE 



Later Jenkin and Shorthose 90 measured the enthalpy of liquid and 
gaseous carbon dioxide at pressures from 63 to 127 atmos. and temperatures 
from +12 to +100 C. This work indicated that the earlier values of 
Jenkin and Pye were in error especially at high pressures. This error was 
in some cases as high as 7 per cent. 



TABLE 25. Iscnthalpic Values for Carbon Dioxide. 

(Data by Burnett) 
Pressure in atmospheres; temperatures in K. ; /* in K. per atmos. 



A* 
T 
A* 
T 
A* 
T 
A* 
T 
A* 
T 
A* 
T 

A* 

T 

A* 

T 
A* 
T 
A* 

T 
A* 



A* 
T 

A* 
T 

A* 

T 

A* 

T 

A* 

T 

A* 

T 





379.94 

0.7080 

356.30 

0.7924 

331.40 

0.9054 

304.30 

1.0760 

272.42 

1.3750 

226.91 

2.1272 

208.69 

2.5786 

181.28 

3.4295 

157.40 

4.343 

120.90 

6.000 

76.00 

8.396 

0.00 
13.580 

(195.21 
(3.7974 
(245.42 
(1.6720 
(265.03 
(0.9102 
(275.86 
(.06978 
(259.24 
(.01096 
(240.54 

(-.00704 
(222.19 

(-.02537 



1 

380.64 

0.7029 

357.10 

0.7860 

332.30 

0.8974 

305.35 

1.0655 

273.88 

1.3590 

229.09 

2.0948 

211.26 

2.5338 

(184.70 

(3.3588 

(161.24 

(4.2514 

(126.80 

(5.832 

(81.40 

(8.114 



( 13., 
( 13.1 



13.38 
13.01 



198.25 
3.6800 
247.07 
1.6312 
265.92 
0.8924 
275.93 
.06936 
259.26 
.01094 
240.53) 

-.00705) 
222.17) 

-.02548 



20 40 60 


72.9 


Vapor Isenthalps 




393.12 404.56 414.39 


420.00 


0.6118 0.5284 0.4564 


0.4154 


370.92 383.40 394.00 


400.00 


0.6748 0.5745 0.4892 


0.4410 


347.99 361.90 373.52 


380.00 


0.6582 0.6348 0.5317 


0.4742 


323.77 339.76 352.85 


360.00 


0.8816 0.7220 0.5914 


0.5200 


297.03 316.46 331.83 


340.00 


1.0885 0.8620 0.6826 


0.5872 


263.56 290.42 310.15 


320.00 


1.5620 1.1470 0.8422 


0.6900 


(252.26) 282.91 304.56 


315.00 


(1.8181) 1.2826 0.9046 


0.7223 


237.43 274.42) 298.85 


310.00 


2.2620 1.4928) 0.9850 


0.7533 


226.49 269.35 295.97) 


307.50 


2.6950 1.6727 1.0380) 


0.7630 


212.44 264.32 293.71) 


305.50 


3.400 1.926 1.091) 


0.7560 


198.40 260.85 292.77) 


304.50 


4.288 2.1915 1.1200) 


0.7264 


Critical Isenthalps 




182.77 260.56 293.70 


304.10) 


5.783 2.463 1.049 


0.6050) 


Liquid Isenthalps 




251.57 281.51 297.44) 


303.50 


2.0194 1.0744 0.5716) 


0.3804 


271.83 287.94 297.79) 


302.00 


1.0210 0.6239 0.3812) 


0.2774 


280.04 290.11 29687) 


300.00 


0.6108 0.4099 0.2751) 


0.2127 


277.16) 278.34 279.39 


280.00 


.06202) .05514 .04901 


.04543 


259.46) 259.67 259.88 


260.00 


.01064) .01027 .00993 


.00973 


240.40 240.29 240.10 


240.00 


-.00723 -.00742 -.00761 


-.00773 


221.66 221.08 220.44 


220.00 


-.02778 -.03040 -.03329 


-.03528 



80 

422.88 
0.3944 
403.05 
0.4165 
383.27 
0.4452 
363.57 
0.4844 
344.00 
0.5405 
324.63 
0.6184 
319.82 
0.6381 
314.97 
0.6500 
312.48 
0.6442 
310.36 
0.6179 
309.09 
0.5724 



305.92 
0.3041 
303.81 
0.2329 
301.41 
0.1846 
280.32 
.04357 
260.07 
.00962 
239.94 

-.00781 
219.74 

-.03464 



100 

430.22 
0.3407 
410.74 
0.3546 
391.43 
0.3728 
372.35 
0.3967 
353.64 
0.4280 
335.27 
0.4540 
330.59 
0.4501 
325.60 
0.4290 
322.77 
0.39<)8 
319.77 
0.3508 
317.42 
0.2926 

313.82 
0.1906 

310.43 
0.1613 
307.48 
0.1423 
304.45 
0.1239 
281.14 
.03873 
260.26 
.00931 
239.79 

-.00801 
218.98 

-.03989 



Note: Values between parentheses () in the main part of this table indicate "mathematical" 
courses of the curves when both liquid and vapor phases arc present. Physically and experi- 
mentally the temperatures and slopes observed are those of the saturation curve for the pressures 
corresponding to the values within the parentheses. 

w Jenkin, C. F. and Shorthose, Proc. Roy Soc. (London), A 99, 352 (1921). 



74 



CARBON DIOXIDE 



I I I 



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tXONf\|lOON-'fQ u 'i-lVO Tf VO r-HQD 




OX 

R! 



* 



f. ^- 10 L 



D t> tx IN o 



.0 



^'-|^>.0 

^ ^H Q O 



I I 



a 





OtO QOtOO OiOtOO to tOi 
^ 00 00 O to to M O\ Ix 00 O 'O ^f 
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vovovptxixtxoooooNO\o\q 

00000000000^ 



*O O OOOtO O l Oir< O 
O "t" * to GO *T IX to ro IxTj 



oq 
ft 



H 



firjtOiOOOtOlOtOlOtoOiO O to toO' 
(Vi^fPOiOiOONQNtxvooO^llx, ~t *f toOC 
rxO p Ol>'-" | OQ <> OvOa\ r OvO Ix O tair 
^q^x^x^Noqooo^o^o^o\qq q i-j i ~j-;f s 
do'ddo'o'ddddd "-" r4 ^-5 1-4^' , 



lOiOO^OtOOOtOOOQOlOO 
(XiOOO'-'^O\'*'tMH^vO>-H Ix Ix 
^IxO'tlX'-'vOT-i^txQ'^lx tx O 
VO SO Ix tx tx 00 00 O\ ON ON O O q O -j 

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qqqqqqqqqqpqq -< q qqqq qqq qq pq 



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^38 



)0SJ 



PHYSICAL PROPERTIES OF CARBON DIOXIDE 



75 



Finally important throttling experiments with carbon dioxide were 
published by Burnett. 01 These experiments were conducted over a period 
of time from 1910 to 1923 and in general agree well with the measure- 
ments of Jenkin and Pye but comparisons with the results of Jenkin and 
Shorthose were not made. The measurements cover the liquid and vapor 
region inclusive of the critical state for pressures from 20 to 75 atmos., 

TAHLK 27. Enthalpy of Dry Saturated Carbon Dioxide in Kg. Cal. per Kg. 
(From Plank and KuprianofT) 



Temp. 

Grit. 

+ 30 

25 

20 

15 

10 

5 



- 5 

- 10 

- 15 

- 20 

- 25 

- 30 

- 35 

- 40 

- 45 

- 50 

- 55 

- 56.6 

60 

- 65 

- 70 

- 75 

- 80 

- 85 

90 

- 95 
-100 



Mollier 

134.14 
141.32 
147.28 
150.20 
152.14 
153.50 
154.49 
155.19 
155.68 
155.97 
156.10 
156.11 
156.00 
155.78 






Langcn 



131.6 


132.25 


139.1 


140.56 




146.71 


149.1 


149.92 


151.4 


151.83 


152.55 


153.24 


153.45 


154.30 


154.1 


155.03 


154.7 


155.48 


155.1 


155.76 


155.2 


155.93 


155.1 


156.02 


154.8 


156.03 


154.45 


155.97 


154.1 


155.84 


153.6 


155.65 


153.3 


155.40 


153.0 


155.09 



Kichel- 
berg 

132.0 
140.1 
146.2 
149.6 
151.7 
153.3 
155.0 
155.8 
156.6 
157.3 
157.7 
158.0 
158.5 
158.7 
158.9 
159.1 
159.2 
159.3 
159.4 



Plank ami 
Kuprianoff 



156.13 
156.41 
156.60 
156.70 
156.72 
156.67 
156.56 
156.39 
156.17 
155.89 
155.57 
155.22 
155.09 
155.06 
154.87 
154.52 
154.06 
153.49 
152.86 
152.16 
151.42 
150.65 



Extra- 
polated 

133.50 
140.95 
147.33 
151.10 
153.17 
154.59 
155.45 
156.13 



and temperatures from 24 to +117 C. Unfortunately these experi- 
ments were made on a gas having air present in various amounts which 
sometimes fluctuated between 0.25 per cent and 1.5 per cent in a single 
experiment. Burnett corrected for this impurity but as Plank and Kupri- 
anofT point out, this injects an uncertainty factor into his results which 
seriously impairs their value. However, these measurements seem to be 
the most complete of any recorded to date and the results for /i at constant 
enthalpy are listed in Table 25 while the isothermal and isobaric values 
are given in Table 26. On plotting these results the curves shown in Figure 
14 were obtained. Burnett found the inversion point in the liquid state 
to be -24 C. 



"Burnett, E. S.. Phys. Rcr. t (2) 22, 590 (1923). 



76 



CARBON DIOXIDE 



Plank and Kuprianoff developed an equation for calculating the enthalpy 
of carbon dioxide over quite a wide range of temperature and pressure. 
This equation may be written in the following form : 



=169.34+ (0.1965+0.000115 /)^8.3724- 



JLV 
100 / 



-(1+0.007424/0 



(23) 



in which the value of / is obtained in kilogram calories per kilogram, when 
p is expressed in kg. per square cm., T in degrees Kelvin, and t in degrees 
centigrade. Values of / obtained by means of this equation are listed in 
Table 27 together with results obtained by various other investigators. 
The last column contains extrapolated values from C. to the critical 
temperature. The extrapolation was very carefully done by these authors 
and the results, without doubt, represent values very close to the true ones. 



TABLE 28. Enthalpy of Liquid Carbon 

Dioxide on the Limit-Curve in 

kcal./kg. 

t, C. Enthalpy 
133.50 
125.90 
118.80 
114.00 
110.10 
106.50 
103.10 
100.00 
96.91 
94.09 
91.44 
88.93 
86.53 
84.19 
81.88 
79.59 



Crit. temp. 

+30 

25 

20 

15 

10 

5 



- 5 
-10 
-15 
-20 
-25 
-30 
-35 
-40 
-45 
-50 
-55 
-56.6 



TABLE 29. -E nthalpy 


of Solid Carbon- 


Dioxide in 


kcaljhg. 


t,C. 


Enthalpy 


-56.6 


25.21 


-60 


23.71 


-65 


21.49 


-70 


19.59 


-75 


17.93 


78.9 


16.73 


80 


16.41 


-85 


14.98 


-90 


13.59 


-95 


12.23 


100 


10.88 



77.30 
75.01 
72.72 
71.97 



The enthalpy of the liquid at any point on the limit-curve may easily be 
calculated by subtracting the latent heat of vaporization from the enthalpy 
of the vapor. In a like manner the enthalpy of the solid may be calculated 
by subtracting the latent heat of sublimation from the enthalpy of the 
vapor. Values calculated in this manner are given in Table 28 and Table 
29. For a more detailed discussion of this subject one should refer to the 
original paper of Plank and Kuprianoff. 

The Entropy of Carbon Dioxide. One may take as a fixed point for 
the entropy of carbon dioxide in the liquid state at C. the value of 
1.00000 k. cal. per kg., and therefore 5*1 = 1.0000 Clausius. Also one may 



PHYSICAL PROPERTIES OF CARBON DIOXIDE 77 

calculate the entropy of carbon dioxide in the vapor state by means of the 
expression given by Plank and Kuprianoff which may be stated as follows : 

^=0.591+0.307888 log r-f 0.00023 T- 0.1039478 log p 

-6.44028 - ^ (140.007424/0 ......... (24) 

/ T \ V 

\100/ 

This equation serves to calculate the entropy of the vapor on the limit 
curve between and 100 C. as well as in the superheated region at 
various temperatures and pressures up to 35 atmos. The entropy of the 
liquid may be calculated from the expression 

S\=Sr-Lr/T .............. (25) 

and for the solid 

S*=Sr-L*/T .............. (26) 

The entropy and enthalpy values of the liquid at C. are given in Table 
30 at various pressures. 

TABLE 30. Entropy and Enthalpy of Liquid Carbon Dioxide at C. 



35.54 1.0000 100.00 

40.0 0.9991 99.90 

50.0 0.9974 99.69 

60.0 0.9957 99.52 

70.0 0.9942 99.37 

75.0 0.9935 99.30 

80.0 0.9928 99.25 

90.0 0.9915 99.14 

100.0 0.9903 99.05 

110.0 0.9892 98.95 

120.0 0.9882 98.87 

In Figure 15 is shown a temperature entropy diagram plotted from the 
data of Plank and Kuprianoff. This is a most useful arrangement of data 
especially from the point of view of compressor design or refrigerating 
engineering. F. B. Hunt of The Liquid Carbonic Corporation, has trans- 
posed the data into English engineering units and constructed a similar 
diagram. Another diagram similar to this has been constructed by Goos- 
mann and Ambro. 02 

The Surface Tension of Liquid Carbon Dioxide. The capillary con- 
stant and surface tension of liquid carbon dioxide was measured by 
Verschaffelt 93 in 1895. Recently a more extensive series of determinations 
was made by Ouinn. 04 Values are given in Table 31 which were taken 
from a large scale diagram on which curves were drawn from the data 

"Goosmann, J. C. f Jce and Refrigeration, 207-14 (1930). 

Verschaffelt, J. E., Vcrhandcl. Akad. Wctenschappcn Amsterdam. 4, 74 (1895). 

"Quinn, E. L., /. Am. Chem. Soc., 49, 2704 (1927). 



PHYSICAL PROPERTIES OF CARBON DIOXIDE 



79 



TABLK 31. Surface Tension of Liquid Carbon Dlox'de. 



Temp. 
C. 

31 

30 

25 

20 

15 

10 
5 


- 5 
-10 
-15 
-20 
-25 
30 
-35 
-40 
-45 
-50 
-56.6 

Extrapolated 



7 in dynes/cm. 
According to Verschaffelt 



1.13 
1.87 
2.71 



8.36 



7 in dynes/cm. 
According to Quinn 

0.00 Cr. Pt. 

0.10* 

0.69 

1.45 

2.12 

2.91 

3.75 

4.65 

5.59 

6.56 

7.57 

8.64 

9.71 
10.79 
11.93 
13.17 
14.55 
15.93 
17.82* Tr. Pt. 



of both Verschaffelt and Quinn. The equation for the surface tension 
curve as given by Quinn is 

............ (27) 



7=0.0653(31.35-0 1 



where y is the surface tension in dynes per centimeter. 

The Dielectric Constant. About the first measurements of the dielec- 
tric constant c for carbon dioxide were made by Linde 95 who found for 
gaseous carbon dioxide, c= 1.060 at 15 C. and and 39 atmospheres ; 1.015 at 
19.9 atmospheres and 1.009 at 9.4 atmospheres pressure. For the liquid he 
found e= 1.608 at -5 C.; 1.583 at C.; 1.540 at 10 C. and 1.526 at 
15 C. Ricggcr 00 found the constant for the liquid at 73 C. to be 
1.001392 and Her/ 97 obtained 1.50 at 10 C. and 1.27 at the critical temper- 
ature. The most recent determinations have l>een made by Keyes and Kirk- 
wood 98 who measured the dielectric constant of the gas at 35, 70 and 100 
C. at a number of different pressures. They also measured the change in 
the dielectric constant of the liquid with change in pressure at a temperature 
of C. Their results for the liquid are as follows : 



P, atm. 



50 75 100 125 150 175 200 

1.6016 1.6187 1.6321 1.6425 1.6526 1.6603 1.6674 



The values obtained for the gas are given in Table 32. 

The Crystal Form. Gaseous carbon dioxide may be frozen into small 
snow-like crystals or into large transparent masses according to the method 
used for producing them. When the solid is produced by the usual method 

"Limit. P., H'tW. An*., 56, 546 (1895). 

"Richer, H., Ann. P1\ys. (4) 59, 753 (1919). 

97 Hcrz, W., 7.. fhvsik. Chcm., 103, 269 (1922). 

M Keyes, F. G., an<l Kirkwood, J. G. t Phys. Krv., 36, 754-61 (1930). 



r 


lempcraturc C. 


~^i 


35 


70 


100 


1.00971 


1.00831 


1.00753 


1.02021 


1.01717 


1.01549 


1.03228 


1.02693 


1.02404 


1.04649 


1.03748 


1.03333 


1.06461 


1.04950 


1.04306 


1.08838 


1.06305 


1.05269 


1.1309 


1.07810 


1.06447 


1.3146 


1.09616 


1.07707 


1.4206 
1.4559 


1.1159 
1.1396 


1.09005 
1.1041 




1.2165 


1.1456 




1.3072 


1.1912 



80 CARBON DIOXIDE 

TABLE 32. The Dielectric Constant for Carbon Dioxide Gas. 
(Data by Keyes and Kirkwood) 

Pressure 
Atmos. 

10 

20 

30 

40 

50 

60 

70 

80 

90 
100 
126 
151 

of expanding the liquid from a cylinder, the result is a snow-like substance 
often spoken of as carbon dioxide snow. When, however, liquid carbon 
dioxide is slowly cooled below the freezing point the result is a transparent 
mass. This ice-like material becomes opaque very quickly as the tempera- 
ture increases because the high coefficient of expansion of the solid produces 
numerous cracks in the block. Liversidge" noted that the crystals belong 
to the cubic system and that they much resembled solid ammonium chloride. 
Behnken 100 made an exhaustive study of the subject and succeeded in mak- 
ing some excellent photographs of the crystals. He formed the crystals by 
admitting limited quantities of carbon dioxide to a glass plate cooled by 
means of liquid air. It was found that by admitting the gas in very small 
puffs the crystals could be grown to any size. These crystals were undoubt- 
edly isometric and their forms were combinations of cubes and octahedra. 
Behnken noted a strange phenomenon in that crystals appeared to explode 
spontaneously. This happened in most cases to the sharpest and best- 
formed crystals and he supposed it to be due to contraction strains set up in 
the crystal on cooling. Wahl 101 also studied crystals of carbon dioxide 
and found them isotropic and in the form of small cubes. X-ray studies 
made by Mark and Pohland 102 showed an elementary cube with a side of 
5.62 A. 

The Index of Refraction. The indices of refraction of various wave 
lengths of light through carbon dioxide at and 760 mm. pressure have 
been measured by a considerable number of investigators. A list of these 
workers with their results is given in Table 33. 

The variation of the index of refraction with temperature and pressure 
for sodium light is expressed by Walker by means of the equation 



.0004510 p 

A*-l=l+- - 
(1+.00380076 

Livcrsidge, A., Chem. News, 71, 152 (1895) ; 77, 216 (1898) 
100 Behnken, II. K. f Phys. Rev., 35, 66 (1912). 
*Wahl, W. f Prof. Roy. Soc. (London), 89 A, 327 (1914). 
*Mark, H. f and Pohland, E., Z. Krist., 61, 293 (1925). 



PHYSICAL PROPERTIES OF CARBON DIOXIDE 



81 



TABLE 33. Refractive Index of Carbon Dioxide at C. and 760 mm. Pressure. 



Wave length 
of light 

White 
White 
White 
0.5352 N 

0.6708 N 



Refractive 
Index 

1.0004497 
1.0004495 
1.0004500 
1.0004507 

1.0004477 



Observer Reference 

Biot and Arago Mem. acad., 7, 301 (1806) 
Dulong Ann. Mm. phys., (2) 31, 154 (1826) 

Jamine Ann. Mm. phys., (3) 49, 282 (1857) 

Kettler "Farbenzerstreuung der Case," Bonn, 

(1865) 
" "Farbenzerstreuung der Case," Bonn, 

(1865) 
Ann. Mm. phys., (4) 20, 136 (1870) 



Compt. rend., 78, 617 (1874) 



Ann. chim. phys., (7) 7, 289 (1896) 

U U U It <i 

Phil. Trans., 201 A, 435 (1903) 

Ann. Physik., (4) 17, 658 (1905) 
< 

Astrophys. J., 28, 435 (1908) 
< < 

"Ueber die Lichtbrechnung der Case 
und ihre Verwcndung in analy- 
tischen Zwccken." Karlsruhe (1910) 

"Die Brcchung und Dispersion dcs 
Lichtes in einigcn Gasen," Breslau, 
(1910) 

where // is the index of refraction, and p is expressed in cm. of Hg. 
Chappuis and Riviere 103 suggested the equation 

Ai-l=.000540 p(l+.W76p+. 0000050 /> 3 ) (29) 

as an expression which showed the change in /i with change in pressure. 
The constants were calculated with values ohtained at 21 C. Pose j pal 104 
found the equations ( 1) 

= constant (30) 



0.4290 N 


1.0004960 


Croullebois 


0.5260 N 


1.0004560 





0.6560 N 


1.0003950 


ti 


White 


1.0004400 





0.4800 N 


1.0004587 


Mascart 


0.6438 N 


1.0004532 





White 


1.0004494 





0.4677 N 


1.0004550 


Perreau 


0.6438 N 


1.0004487 


U 


0.5890 N 


1.0004510 


Walker 


0.4359 N 


1.0004563 


Koch 


0.8678 N 


1.0004579 





0.3342 N 


1.0004668 


Rcntbchlcr 


0.5771 N 


1.0004487 





0.4359 N 


1.0004589 


Stuckert 


0.6708 N 


1.0004466 


n 


0.4472 N 


1.0004568 


Gruschke 


0.6678 N 


1.0004475 






and 



D 
(/-I) 



= constant (31) 



hold with a fair degree of accuracy for pressures up to 19 atmos. 

The index of refraction of liquid carbon dioxide was found by Bleek- 
rode lor ' to be 1.999 at 12.5 C; 1.192 at 15.5 C; 1.186 at 18.5 C. and 
1.173 at 24 C. 

Adsorption. Most of the earlier investigations on the adsorption of 
carbon dioxide on the surface of solid bodies were directed towards its 
action on minerals and glass. Scheermesser 100 made an investigation of the 

108 Chappuis, J., and Riviere, C., Compt. rend., 103, 37 (1886). 

10 *P OS ejpa1, V., /. phys. radium, 2, 85 (1921); 4, 451 (1923). 

Bleekrode, L., Proc. Roy. Soc. (London), 37, 339 (1884). 

Scheermesser, F., Vierteljahrsscnr. prakt. Pharm., 20, 570 (1871). 



82 



CARBON DIOXIDE 



adsorption of carbon dioxide by sand and clay and noted an increase in 
the adsorption when the mixture was wet, also that carbon dioxide was given 
off in the sunlight and readsorbed in the shade. Hannay 107 observed that 
carbon dioxide under pressure was adsorbed by glassy silicates, borates, and 
phosphates. Bunsen 108 studied the adsorption of carbon dioxide on glass 
and made some very interesting observations on the rate and the probable 
mechanism of the reaction. In the light of our present knowledge, however, 
these observations are of no special importance. Matignon and Marchal 100 




Pressure in mm. 



FIGURE 16. Adsorption of Carbon Dioxide by Silica Gel. 
(Data by Patrick, Preston and Owens) 

determined the nature of the action of carbon dioxide under 10 atmos- 
pheres pressure on quarts, mica, dioptasc, wdlastonite, talc, asbestos and 
glass. 

At present most of the interest in the adsorption of carbon dioxide on 
solids seems to be directed towards silica gel and activated carbon as the 
adsorbents. This condition has developed because of the practical use 
of these substances for the purification of carbon dioxide in the manufac- 
turing plant and also because of certain theoretical ideas that recently have 
been advanced. The action of carbon dioxide on silica gel has been studied 
by Patrick, Preston and Owens 110 and the isotherms shown in Figure 16 

10T Hannay, J. B., Proc. Roy. Soc. (London), 32, 407 (1881). 

108 Bunsen, R.. Wied. Ann., 20, 545 (1883); 22, 145 (1884); 24, 321 (1885); 29, 161 (1886); Phil 
Mag. (5) 22, 530 (1886). 

109 Matignon. C., and Marchal, G., Compt. rend., 170, 1184 (1920). 

" Patrick, W. A., Preston, W. C., and Owens, A. E., J. Phys. Chem., 29, 421-34 (1925). 



PHYSICAL PROPERTIES OF CARBON DIOXIDE 



83 



were constructed from their data. From these curves it becomes evident 
at once that the degree of adsorption is a function of the temperature as 
well as of the pressure and, as will be shown later, of the previous history 
of the sample of adsorbing material. Use is made of these facts in the 
process of de-gassing adsorbing substances by submitting them to very high 
temperatures and to very low pressures. Perhaps the most important 
theoretical idea advanced by Patrick and his co-workers is that the adsorbed 
gas exists as a liquid in the pores of the solid. Thus the surface tension of 
the liquefied gas would play an important part in the process of adsorption. 
How this surface action of the liquid enters into the problem is indicated 
by the equation which has been developed by Patrick and his associates. 
This equation may be put into the form 



/P7\i 

=K( )*, 
\P.J 



(32) 




Prscur in mm. 

FIGURE 17. Adsorption of Carbon Dioxide by Silica Gel. 
(Data by Magnus and Kieffcr) 

where V is the volume of liquefied gas adsorbed per gram of gel, P is the 
equilibrium pressure, P is the ordinary saturation pressure at the temper- 
ature at which the surface tension is measured, y the surface tension of 

the liquefied gas, and K and - are constants dependent entirely upon the 
structure of the gel. The constants for carbon dioxide at C. have been 

calculated as -=0.866 and #=0.145 while at 20 C. the corresponding 
n 

values for these constants are 0.898 and 0.558. This equation is of little 



84 



CARBON DIOXIDE 



importance from a practical point of view at present but is of considerable 
theoretical interest. 

How the history of the adsorbent affects its action as an adsorbing 
agent is easily seen by comparing the isotherms just given in Figure 16 
and those of Magnus and Kieffcr 111 which arc shown in Figure 17. The 
silica gel used in the first investigation by these authors was made by treat- 
ing sodium silicate with C. P. hydrochloric acid. The resulting gel was 




Pressure in mm 

FIGURE 18. The Adsorption of Carbon Dioxide on Silica Gel at C. 

washed for two weeks with running water, air dried for eleven days and 
refluxcd with aqua rcgia for fifteen hours. It was again washed with 
distilled water for ten clays, air dried and heated in an electric furnace in 
an atmosphere of dry air to a maximum temperature of 400 C. and after 
grinding and sizing it was reheated to 550 C. for twelve hours. It then 
showed a water content of 3.64 per cent. A second sample was heated two 
weeks longer at a temperature of 700 to 750 C. and then showed a water 
content of 1.28 per cent. The gel used by Magnus and Kieffer was also 
made from sodium silicate and purified with aqua regia but the de-gassing 
was accomplished in a vacuum oven at 300 C. and a continuous pressure 
of 0.003 mm. After this treatment the sample showed a water content of 
5.4 per cent. 

Kalberer and Mark 112 found that the initial portion of the adsorption 
isotherms for carbon dioxide on many silica gels are linear for a consid- 
erable distance which indicates adsorption on a plane surface. For other 

111 Magnus, A., and XielTer, R., Z. anorg. allfjcm. Chcm., 179, 215-32 (1929). 
"'Khlberer, W., and Mark, H., Z. physik. Chcm., Abt. A 139, 151-62 (1928). 



PHYSICAL PROPERTIES OF CARBON DIOXIDE 



85 



gels the initial portion of the isotherms exhibits a much faster increase in 
the amount adsorbed than in the succeeding linear region of the curve which 
indicates active areas in the gel. Later Kalberer and Schuster 113 observed 
that some isotherms have convex curvatures in the initial portion which 
indicates capillary condensation of carbon dioxide to a liquid in the gel. 
All these effects may be superimposed on each other. Comparison of 
isotherms of these investigators made with different samples of silica gel, 
and plotted in Figure 18, again shows how the history of the sample affects 
not only the degree of adsorption but also the shape of the curve. The 
data from which Curve I was plotted resulted from a gel de-gassed at 200 
C, Curve II from a gel de-gassed at 350 C. and Curve III from a gel 
de-gassed at dark red heat for about one hour. Figure 19 shows the same 
isotherms at higher pressure and it is of interest to note the change in the 
relative order of these three curves. Isotherms for carbon dioxide on silica 
gel were also constructed from the data by Magnus and Kalberer and they 
check closely the values of Magnus and Kieffer. 

Some later measurements on the adsorption of gases on silica gel have 
been made by Sameshima 114 who determined the velocity and amount of 




FIGURE 19. The Adsorption of Carbon Dioxide on Silica Gel at C. 
(Curve Ib at 10 C.) 

adsorption of gases by dehydrated silica gel at 25 C. and one atmosphere 
pressure. Under these conditions 1 gram of gel adsorbed 46.53 cc. of 
ammonia, 6.4 cc. of carbon dioxide and 4.5 cc. of ethylcne. 

The most active adsorbing agent for carbon dioxide seems to be char- 
coal. As in the case of gels the history of the adsorbing agent exerts a 
considerable influence on the quantity of carbon dioxide it is capable of 

118 Kalberer, W., and Schuster, C. f Z. fihysik. Cftem., Abt. A 141, 270-96 (1929). 
114 Sameshima, J., Bull. Chem. Soc. t (Japan), 7, 133-5 (1932). 



86 



CARBON DIOXIDE 



taking up. Yet when the isotherms of the various investigators are plotted 
together the similarity of the curves is quite remarkable. Such plots have 
been made on a large scale graph for the purpose of comparing the results 
of several investigators, and these curves gave the values shown in Table 34. 



TABLE 34. Showing the Volume of Carbon Dioxide (cc. at 0C. and 760 mm. 
Per gram) Adsorbed on Charcoal According to Various Investigators. 

Temperature = C. 



Equil. Magnus Richardson 

pressure and Richardson Homfray and 
in mm. Kalberer Woodhouse 



SO 
100 
ISO 
200 
250 
300 
350 
400 
450 
500 
550 
600 
650 
700 



19.7 
27.4 
32.7 
36.3 
39.0 
41.2 
43.4 
45.5 
47.6 
49.7 



20.0 
28.5 
34.3 
39.0 
42.6 
45.3 
47.4 
49.2 
50.8 
52.3 
53.8 
55.4 



18.6 
282 
35.0 
40.3 



16.1 
25.7 
32.7 
38.6 
43.7 
48.2 
52.0 
55.4 
58.6 
61.7 
64.6 
67.5 
70.0 
72.3 



Titoff 

21.7 
30.6 
37.3 
42.5 
46.3 
49.3 
52.0 
54.4 
56.4 
58.2 
59.9 
61.6 
63.1 
64.5 



Magnus 

and 

Kratz 

19.7 
30.1 
38.2 
45.1 
51.8 




PreMur* m mm. 



FIGURE 20. Adsorption of Carbon Dioxide by Charcoal. 
(Data by Homfray) 

The adsorbing material used by Miss Homfray 115 was made by heating 
cocoanut shell fragments in an oven for about five hours. The granules, 



PHYSICAL PROPERTIES OF CARBON DIOXIDE 



87 



which were about 10 cu. mm. in size, were then boiled with nitric acid to 
remove the mineral matter and after washing with distilled water were 
dried by strong heating under reduced pressure. The eight isotherms 
shown in Figure 20 were plotted from data obtained by Miss Homf ray. 

Titoff 110 made his charcoal by distilling cocoanut shells under sand. The 
product was then heated to about 550 C. in a long combustion tube under 




Pressure In m.m. 

FIGURE 21. Adsorption of Carbon Dioxide by Charcoal. 
(Data by Titoff) 



the simultaneous action of a water pump. The grains of charcoal were 
then sized so they varied from 200 to 20 mg. with an average of 77 mg. 
The mineral matter was removed with acid and after drying the charcoal 
was de-gassed in the reaction flask at 400 C. under a pressure of 0.001 
to 0.003 mm. of mercury. The isotherms obtained by this investigator are 
shown in Figure 21. 

Richardson's 117 results were obtained with an adsorbent made by heating 
fragments of cocoanut shells in an iron tube immersed in a bath of molten 
antimony. The temperature was kept near 630 C. for about one hour. 

"Titoff, Alexander, Z. physik. Chem., 74, 641-78 (1910). 

117 Richardson, L. B., and Woodhouse, J. C., /. Am. Chem. Soc., 45> 2638-53 (1923). 



88 



CARBON DIOXIDE 



The results listed under Richardson and Woodhouse were obtained on a 
steam-activated charcoal, obtained from the Barneby Cheney Engineering 
Company. The de-gassing was accomplished at 425 for four hours under 
a vacuum of less than 1 mm. 

Unfortunately details concerning the manufacture of the charcoal used 
by Magnus and Kalberer 118 are lacking. The de-gassing took place at a 
temperature of 600 C. 




PntMur in mm. 



FIGURE 22. Adsorption of Carbon Dioxide by Various 
Solid Substances at C. 

Magnus and Kratz 110 made their charcoal by the destructive distillation 
of beechwood at 540 C. and a pressure of about 0.15 mm. of mercury. 
The ash content was 1.69 per cent based on the dry material. The charcoal 
was finally de-gassed for 5 days at a temperature of 320 to 340 C. during 
which a vacuum of less than 0.001 mm. was maintained on the system. 

Hirano 120 found that cane sugar charcoal increased its efficiency as an 
adsorbent for carbon dioxide with temperatures of carbonation up to 800 

118 Magnus, A., and Kalberer, W., Z. anorg. allgem. Chcm., 164, 345-56 (1927). 
Magnus, A., and Kratz, H., Z. anorg. allf/em. Chcm. 184, 241-71 (1929). 
120 Hirano, H., /. Chem. Soc. Japan. 50, 439-40 (1929). 



PHYSICAL PROPERTIES OF CARBON DIOXIDE 89 

but at 900 C. the adsorbing effect was slightly decreased. Allmand and 
Chaplin 121 determined the isotherms for nine samples of charcoal at 25 C. 
and a pressure range from 0.01 to 0.15 mm. Burrage 122 studied the 
adsorption isothermal of carbon dioxide by a static method over a pressure 
range from 0.04 to 81 mm. while Magnus and Giebenhain 123 made adsorp- 
tion determinations of carbon dioxide on six different charcoals at very 
low pressures. Remy and Hcnc 124 made a comparison between the dynamic 
and static methods for determining adsorption isotherms for carbon dioxide 
and found that the dynamic method gave the lower values. 

According to the researches of Lanning 123 manganese dioxide ranks 
in about the same class as silica gel as an adsorbent for carbon dioxide. 
He prepared his manganese dioxide according to the method proposed by 
Fremy. 120 Granules of about 6 to 10 mesh were selected and the adhering 
water separated by means of a suction filter after which they were subjected 
to a pressure of several tons per square inch for 48 hours. The compressed 
cakes were then dried in an air bath for three hours at a temperature of 
110 C. Four other samples were used for the adsorption tests but the 
final treatment of these was slightly different from the one just described. 
The results obtained with this adsorbing material are shown by a curve 
in Figure 22. The other isotherms differed only slightly from this one. 
Foote and Dixon 127 showed that the presence of water on the manganese 
dioxide decreased the adsorbing capacity considerably. 

The effect of catalytic adsorption of carbon dioxide on metallized silica 
gels was studied by Reyerson and Swearingen. 128 The effect on such sub- 
stances would in general be that of silica gel plus any specific adsorption 
which might be due to the metals deposited as films on the surface of the 
gel. The results obtained in this investigation are shown in Table 35. 

TABLE 35. The Adsorption of Carbon Dioxide by Metallised Silica Gels at C. 

The values in the table are cc. of carbon dioxide (0 and 760 mm.) adsorbed 
by one gram of adsorbent. 

(Data by Reyerson and Swearingen) 

Pressure in mm. of Hg. .100 200 300 400 500 600 700 

Silica gel 4.98 7.15 9.25 11.45 13.65 15.70 17.80 

Silverized gel 4.25 7.30 9.80 12.20 14.55 16.80 19.20 

Platinized gel 4.65 8.00 10.75 13.00 14.80 16.60 18.45 

Palladized gel 7.20 12.30 15.90 19.30 23.00 26.20 29.60 

Copperized gel 5.30 8.50 11.20 13.90 16.50 19.20 21.85 

The uncertainty regarding the chemical nature of activated charcoals 
has led to researches in which graphite was used as the adsorbing agent. 

12t Allmand, A. J., and Chaplin, R., Proc. Rov. Soc. (London), A 132, 460-79 (1931) 

123 Bun-age, L. T., /. Pliys. Chcm., 36, 2272-83 (1932). 

123 Magnus, A., and Giebcnhain. H., Z. phyrik. C/irm., A 164, 209-22 (1933). 

Remy, H., and Hene, W. f Kalloid- Z., 62, 154-7 (1933). 

""Lanning, C. K., /. Am. Chcm. Soc., 52, 2411-15 (1930). 

"Fremy, Compt. rend., 82, 1231 (1879). 

" 7 Foote, II. W., and Dixon, J. K.. /. Am. Chcm. Soc., 52, 2411 (1930). 

Reyerson, L. H., and Swearingen, L. E., J. Phys. Chcm., 31, 88-101 (1927). 



90 CARBON DIOXIDE 

Magnus and Kratz 129 conducted an investigation on the adsorption of Cey- 
lon graphite and Acheson graphite. In the former investigation the press- 
ures were not carried high enough to make a good isotherm on the scale we 
have used, but their results on Acheson graphite are shown for C. in 
Figure 22. In order to separate the curve from the pressure axis the 
volumes of gas are based on 10 grams of graphite instead of 1 gram as in 
the case of all other isotherms. Ix>wry and Morgan 130 made an adsorbing 
material from graphite having an adsorbing capacity for carbon dioxide 
practically the same as silica gel. They treated powdered Ceylon graphite 
with HoFo and after washing and drying, digested with fuming nitric acid. 
The product which is often called "graphitic acid" was exploded in a 
vacuum producing "pyrographitic acid". This substance has been shown to 
be simply finely divided graphite. Blocks made by compression of this 
material had an adsorptive capacity of about one-third to one-fourth that 
of the best charcoal. Of the several isotherms they constructed, one has 
been selected for reproduction in Figure 22. 

In order to set some idea of the relative adsorptive capacities of char- 
coals, gels etc., representative curves for each class of substances have 
been plotted in Figure 22. Perhaps the most interesting thing shown by 
this diagram is the high adsorptive capacity of beechwoocl charcoal. Appar- 
ently this is the best adsorbent yet found for carbon dioxide, at least under 
the pressures indicated by the upper portion of this curve. 

Various other substances have been investigated more or less extensively 
for their adsorptive action on carbon dioxide. Munro and Johnson 131 
found alumina a good adsorbing agent. Nikitin and Jurjew 132 studied the 
action of carton dioxide on gels of TiOo and SnOu, with the following 
results : 

Substance 

SnO 2 
TiO a 
TiO 2 

The weight of the gel in each case was 4.2717 grams and the amount of 
gas adsorbed and indicated in the last column was calculated to standard 
conditions. Kalberer and Mark 133 determined the adsorptive action of 
aluminum foil for carbon dioxide and from their results calculated the 
thickness of the layer of adsorbed carbon dioxide on the foil, at 0, 45 
and 65 C., to be of the order of 1.5 X 10 8 cm. Adsorption of carbon diox- 
ide on bare and oxygen covered surfaces of silver has been investigated 
by Drake and Benton. 134 Bare silver showed only an instantaneous physi- 
cal adsorption for carbon dioxide at 78 and C. with a heat of adsorp- 

Magnus. A., and Kratz, IT., Z. anora. allrjcm. Chcm., 184, 241-72 (1929). 

Lowry, II. H., and Morgan, S. O., /. Phys. Chcm., 29, 1105 (1925). 

m Munro, L. A., and Johnson, F. M. G. t I*d. Eng. Chcm., 17, 88 (1925). 

189 Nikitin. N. J., and Jurjew, W. J., Z. anorq. allcjcm. Chcm., 171, 281-4 (1928). 

Kalberer, W., and Mark, IT., Z. physik. Chcin., Abt. A 139, 151-62 (1928). 

Drake, L. C., and Bcnton, A. F., J. Am. Chew. Soc., 56, 506-11 (1934). 



Drying 
temp. C. 


Water con- 
tent in % 


Pressure of 
CO a in mm. 


Adsorption 
temp. C. 


Adsorption 
incc. 


400 
250 
175 


09 
4.8 
7.8 


738.4 
741.0 
754.2 


127 
14.0 
15.3 


21.2 
127.8 
123.3 



PHYSICAL PROPERTIES OP CARBON DIOXIDE 91 

tion of about 5 kg.-cal. On silver surfaces occupied by adsorbed oxygen, 
activated adsorption of carbon dioxide occurred between and 200 C. 
Silver surfaces occupied by silver oxide reacted with carbon dioxide to form 
silver carbonate at temperatures as low as 56 C. Isotherms for the adsorp- 
tion of carbon dioxide on finely divided gold were constructed by Magnus 
and Klar 135 for 0, 20 and 40 C. and pressures up to 520 mm. of mer- 
cury. It was found that at low pressures the adsorption does not follow 
Henry's law, the adsorption being always greater than that corresponding 
with the law. Somewhat later Magnus and Klar 130 studied the adsorption 
isotherms of carbon dioxide at the same temperatures on pyrophoric iron 
and gold powder. The adsorption of carbon dioxide on palladium oxide 
has been studied by McKimiey. 137 Bosworth 138 found that mercury drops, 
falling through a mixture of sulfur dioxide, carbon dioxide and water 
vapor, selectively adsorbed these gases on the surface of the mercury as 
monomolecular layers. 

Interesting experiments were made by Bangham and Fakhoury 130 in 
which they measured the expansion of charcoal on adsorption of gases 
and vapors. They found the expansion directly proportional to the square 
of the amount of gas adsorbed. The expansion caused by the adsorption 
of carbon dioxide amounted roughly to 0.101 per cent at 30 C. and one 
atmosphere pressure. In some later experiments 140 these investigators 
derived the qualitative expression 

x=K (33) 

S s 

to represent the linear expansion .r of a charcoal rod during the adsorption 
of gases. In this equation s is the weight of the gas taken up per unit 
weight of adsorbent while K and .V are constants. 

Druckcr 141 made a study of the effect of adsorption on the coefficient of 
friction of a binary mixture of gases passing through a glass tube. He 
calculated the thickness of the adsorbed layers of carbon dioxide on the 
surface of the glass to be l.Ox 10~ 8 cm. and that of water to be 5.5 X 1Q- 8 
cm. The coefficient of friction is not a linear function of the gas composi- 
tion and he explains this as being due to the selective adsorption of the 
various components. The adsorption of carbon dioxide and nitrous oxide 
on charcoal has been determined by Richardson and Woodhouse as single 
gases and also in mixtures of varying composition. The replacement of one 
gas already adsorbed on charcoal by another, is rather an interesting reac- 
tion. The replacement takes place rapidly at first but the speed gradually 
becomes slower and slower and complete replacement never takes place. 

185 Matrntis, A., and Klar, 1?., Siebcrt Festsohr. 1931, 235-9. 

" Magnus, A., and Klar, H., Z. physik. Oirm., A 161, 241-54 (1932). 

McKitmey, P. V., /. Am. Chcm. Soc., 55, 3626-32 (1933). 

"Bnsworth, R. C. f Train. Fantday Soc.. 28, 896-902 (1932). 

189 Bangham, D. Tf., and Fakhoury, N., Nature, 122, 681-2 (1928). 

"Bangham, D. II., and Fakhoury, N., Proc. Roy. Soc. (London), A 130, 81-9 (1930). 

141 Drucker, Carl, Z. Elektrochcm., 35, 640-4 (1929). 



92 CARBON DIOXIDE 

That is to say, the amount of the second gas adsorbed never becomes equal 
to that which would have been adsorbed from a mixture of the same com- 
position thoroughly mixed before being admitted to the charcoal. The 
adsorption of carbon dioxide on activated charcoal in the presence of carbon 
tetrachloride and hydrogen cyanide was determined by Chaplin 142 on 
several charcoals at 25 C. His results show that adsorbed singly they 
impede but do not change the nature of the adsorption process for carbon 
dioxide. When adsorbed together, however, they suppress the irreversible 
adsorption of carbon dioxide completely and allow only superimposed 
simple adsorption. A theoretical treatment of this subject from a thermo- 
dynamic standpoint has been made by Krichevskii 143 who deals with the 
kinetics of the oxygen-carbon dioxide system on silica gel in terms of 
adsorption of the two phases. 

The Heat of Adsorption. Because of its theoretical importance the 
heat of adsorption of vapors and gases have assumed special importance 
in recent researches. In general it may be said that the heat of adsorption 
is not only a function of the temperature at which the adsorption takes place 
but also of the equilibrium pressure of the system. In the region where 
Henry's law holds, i. e. at very low pressures, the degree of adsorption is 
in many cases practically a linear function of the pressure. This region 
has been studied extensively not only for the degree of adsorption but the 
heat of adsorption as well. In some cases the ratio of adsorption to the 

TABLE 36. Heat of Adsorption of Carbon Dioxide on Various Adsorbing Agents 
in the Region of Validity of Henry's Laiv. 

A 

Adsorbent P Q in gram cal. per mole of gas adsorbed 

25 12.5 25 37.5 

Charcoal 1 15.9 7900 about 7700 

Charcoal 2 15.4 7720 

Charcoal 1 14.1 7790 7570 7320 

Charcoal 1 12.2 7550 7320 7040 

Charcoal 2 11.6 7520 about 7300 

Charcoal 1 8.2 7250 7030 6800 

Silica gel 2.37 6958 

Silica gel 2.44 7065 6830 6600 

Graphite A 0.0603 7730 7540 7320 

Graphite C 0.0214 7700 7460 7230 

Graphite C 0.0182 7490 7250 7020 

Charcoal samples marked 1 were made from beechwood. those marked 2 were made from 
cocoanut shells. Graphite A was Acheson graphite and graphite C was Ceylon graphite. A is 
the adsorption coefficient of carbon dioxide in micromoles ( ~10~* mole), p is the equilibrium 
pressure expressed in mm. of Hg. 

pressure remains quite constant up to a pressure of about 10 mm. but in 
others it shows a tendency to change after a pressure of 2 to 3 mm. has 
been reached. The work of Magnus and Kratz 144 is interesting as it com- 
pares the heat of adsorption of several samples of charcoal and other 

Chaplin, R., Trans. Faraday Soc. t 30, 249-60 (1934). 

" Krichevskii, I. R. f /. Phys. Chem. (U. S. S. R.), 5, 742-9 (1934). 

144 Magnus, A., and Kratz, H., Z. anorg. allgcm. Chem., 184, 241-71 (1929). 



PHYSICAL PROPERTIES OF CARBON DIOXIDE 93 

adsorbents in the region where Henry's law is valid. These data are given 
here as Table 36. 

Magnus and Giebenhain also measured the heat of adsorption on a puri- 
fied charcoal at and at 25 C. Tables 37, 38, 39 and 40 give their 
results. 

TABLE 37 TABLE 38 

Adsorption Temp. C. Adsorption Temp. C. 

p in mm. Q in gm.-cal./mole p in mm. Q in gm.-cal./mole 

0.92 8467 0.0765 12462 

2.00 8247 0.484 10496 

3.54 8184 0.89 9597 

6.90 8091 4.89 8542 

10.00 7917 18.30 7910 

56.40 7506 26.90 7680 

211.10 7283 58.20 7384 

505.70 6739 70.10 7268 

150.30 7194 

278.80 7062 

521.10 7006 

TABLE 39 TABLE 40 

Adsorption Temp. C. Adsorption Temp. 25 C. 

p in mm. Q in gm.-cal./mole p in mm. Q in gm.-cal./mole 

0.232 8254 0.517 7710 

0.413 8194 0.867 7766 

0.742 8126 1.905 7735 

1.641 7977 4.015 7558 

2.329 7925 6.300 7517 

6.800 7732 13.300 7434 

The heats of adsorption of carbon dioxide on silica gel are in general 
somewhat lower than on charcoal at the same equilibrium pressures. Sev- 
eral investigators have calculated the heat of adsorption by means of the 
Clausius-Clapeyron equation but recently a number of direct measurements 

TABLE 41 TABLE 42 

Adsorption of Carbon Dioxide on Silica Adsorption of Carbon Dioxide on Silica 

Gel at C. Gel at 25 C. 

p in mm. Q in gm.-cal./mole p in mm. Q in gm.-cal./mole 

0.630 7371 1.350 6958 

0.800 7343 2.430 6936 

1.010 7290 3.250 6942 

1.300 7398 4.746 6950 

1.498 7343 5.18 6<>42 

1.609 7362 9.15 6925 

2.235 7300 15.20 6882 

5.50 7270 19.15 6800 

8.70 7290 24.40 6800 

18.20 7150 31.00 6795 

36.40 7104 41.75 6773 

63.45 7033 55.90 6712 

92.50 6997 78.90 6700 

122.10 6670 

"'Kalberer, W. f and Mark. H. f Z. ph-vsik. Chcin., Abt. A. 139, 151-62 (1928). 



94 



CARBON DIOXIDE 



have been made. Kalberer and Mark 145 obtained a value of 6200 gram-cal. 
per mole of carbon dioxide adsorbed, by calculation from the data obtained 
in the linear portion of their isotherm, while from the steeper portion of 
the isotherm they obtained an average value of 7500 calories. Magnus and 
Kalberer also studied the heat of adsorption on silica gel and give an elabor- 
ate theoretical discussion concerning it. In Tables 41 and 42 are given the 
results obtained by Magnus and GieJDenhain by the use of this adsorbent. 

Solubility. The usual methods of expressing the solubility of a gas 
in a liquid are: (1) The Bunscn Absorption Coefficient a. This is the 
volume of gas reduced to standard conditions which at the temperature of 
the experiment, is dissolved by one volume of the solvent, the partial pres- 
sure of the gas being 760 mm. This may be calculated at various tempera- 
tures by means of the equation 



F(H-0.003670 



(34) 



where a is the absorption coefficient, v the volume of the solute and V the 
volume of the solvent. (2) The Ostuvld Solubility Expression I This is 
the ratio of the concentration of the gas in the liquid to its concentration in 
the gas phase or l=v/V. This expression differs from the Bunsen Absorp- 
tion Coefficient in that the volume v of the dissolved gas is not reduced to 
standard conditions. 

Other methods of expressing gas solubilities are also used, for example, 
the Kuenen Absorption Coefficient and the Raoult Absorption Coefficient, 
but an attempt will be made in this work to confine all data to the first two 
methods of expression. 

The Effect of Temperature on Solubility. The most extensive data 
we have on the solubility of carbon dioxide in water at different tempera- 

TABLE 43. The Solubility of Carbon Dioxide in Water at Various Temperatures. 



Temp. 
C. 


a 


lO-'x/C 


Temp. 
C. 


a 


IO-'XA: 


Temp. 
C. 


a 


IQ-'XAT 





1.713 


0.552 


13 


1.083 


0.873 


26 


0.738 


1.27 


1 


1.646 


0.575 


14 


1.050 


0.901 


27 


0.718 


1.30 


2 


1.584 


0.597 


15 


1.019 


0.929 


28 


0.699 


1.34 


3 


1.527 


0.619 


16 


0.985 


0.958 


29 


0.682 


1.37 


4 


1.473 


0.642 


17 


0.956 


0.987 


30 


0.665 


1.41 


5 


1.424 


0.666 


18 


0.928 


1.018 


35 


0.592 


1.58 


6 


1.377 


0.689 


19 


0.902 


1.049 


40 


0.530 


1.77 


7 


1.331 


0.713 


20 


0.878 


1.079 


45 


0.479 


1.95 


8 


1.282 


0.738 


21 


0.854 


1.110 


50 


0.436 


2.15 


9 


1.237 


0.764 


22 


0.829 


1.140 


55 


0.394 




10 


1.194 


0.791 


23 


0.804 


1.170 


60 


0.359 


2.57 


11 


1.154 


0.819 


24 


0.781 


1.209 








12 


1.117 


0.845 


25 


0.759 


1.247 









PHYSICAL PROPERTIES OF CARBON DIOXIDE 



95 



tures are found in the works of Bohr. 140 The temperature range covered 
by his works extend from to 60 C. and it is interesting to note the close 
agreement of his results with many determined more recently. Table 43 
gives these data together with the values of K (Henry's law constant) 
calculated by Loomis. 147 These values for K were obtained by means of 
the expression 

K=P A /XA (35) 

where PA is the partial pressure of A and XA is the mole fraction of A in 
the solution. 

The Effect of Pressure on Solubility. The relation between the sol- 
ubility of carbon dioxide in water and its pressure above the solution was 
worked out very early (1882) by Wroblewski 148 and his results are still 
considered of great value. When his data are plotted on a large scale 
graph the smoothness of the curves gives one considerable confidence in the 
accuracy of the results. In the present case these large scale plots were 

TABLE 44. Solubility of Carbon Dioxide in Water at Pressures above 1 Atmosphere. 

(Data by Wroblewski) 



p 

in atmos. 


a 



12 a 4 


P 
in atmos. 


a 



12*4 


1 


1.797 


1.086* 


16 


23.00 


14.32 


2 


3.56 


2.15 


17 


24.00 


15.05 


3 


5.32 


3.20 


18 


24.92 


15.78 


4 


7.02 


4.22 


19 


25.84 


16.48 


5 


8.65 


5.15* 


20 


26.65 


17.11* 


6 


10.28 


6.10 


21 


27.50 


17.84 


7 


11.78 


7.00 


22 


28.30 


18.48 


8 


13.20 


7.88 


23 


29.10 


19.23 


9 


14.65 


8.75 


24 


29.87 


19.75 


10 


16.03 


9.65* 


25 


30.55 


20.31* 


11 


17.25 


10.45 


26 


31.25 


20.95 


12 


18.50 


11.25 


27 


31.90 


21.54 


13 


19.70 


12.04 


28 


32.55 


22.14 


14 


2085 


12.80 


29 


33.16 


22.72 . 


15 


21.95 


13.55 


30 


33.74 


23.25* 



Values marked * are original data. 

made for the two temperatures at which data are available and readings 
made from these curves furnished the values shown in Table 44. Wroblew- 
ski called the results he obtained, the coefficient of saturation but this is, 
without doubt, the Bunsen Absorption Coefficient. 

"Bohr, C., Ann. Physik., 68, 500 (1899). 

"'Loomis, A. L., "International Critical Tables," 3, 260, 265, McGraw-Hill Publishing Co., 
New York. 

"Wroblewski, S., Compt. rend., 94, 1335 (1882). 



96 



CARBON DIOXIDE 



Solubility measurements at very high pressures have been made by 
Sander. 149 His results were obtained by means of the well-known Cailletet 
apparatus using in one case 0.210 cc. of water and in a second set of deter- 
minations 0.102 cc. of solvent. The water was measured into the Cailletet 
tube and the decrease in the quantity of gas after solution at each pressure 
was determined. It is at once evident that this method of determining 
solubilities is subject to considerable error and this fact is more forcefully 
impressed on one by attempting to plot isotherms from the reported data. 
The points are so widely scattered that one has considerable difficulty in 
even guessing the probable location of the curve. The data perhaps have 
some value, however, on account of the very high pressures to which they 
were extended and the isotherms give one some idea of the conditions 
under which Henry's law becomes valid. These isotherms have been con- 
structed by the authors, on a large scale and the probable location of the 
curve in each case has been determined. Readings from these curves are 
recorded in Table 45. 

TABLE 45. Solubility of Carbon Dioxide in Water at High Pressures. 
(Data by Sander) 





Cc. of CO, 






Cc. of CO 2 


Temp. Pre f n sure 
o p^ in 

*" kg./sq. cm. 


Reduced to 
Ikg./sq.cm. 
dissolved by 


Temp. 
C 


Pressure 
in 
kg./sq. cm. 


Reduced to 
Ikg./sq.cm. 
dissolved by 




lcc.ofH 2 O 






1 cc. of H P O 


20 25 


17.8 


60 


90 


23.1 


30 


19.5 


<( 


100 


26.2 


40 


23.3 


(i 


110 


29.6 


50 


27.5 





120 


33.2 


55 


30.1 


100 


60 


8.9 


35 30 


11.8 




70 


9.9 


40 


15.0 




80 


11.0 


50 


18.6 




90 


12.2 


60 


22.7 




100 


13.5 


70 


27.5 




110 


14.8 


80 


32.9 





120 


16.1 


60 40 


10.4 


tt 


130 


17.5 


50 


12.4 





140 


18.9 


60 


14.7 


H 


150 


20.3 


70 


17.3 


tt 


160 


21.9 


80 


20.1 


tt 


170 


23.4 



The Effect of Temperature and Pressure Changes Expressed in 
Pounds per Square Inch and in Degrees Fahrenheit. A very useful solu- 
bility table has been calculated by Heath 150 in which the data are expressed 
in English engineering units. These data are especially useful to the 
bottling industry and they are here reproduced as Table 46. 

" Sander, W., Z. physik. Chem., 78, 513-49 (1912). 

1150 Heath, W. P., Privately Printed, Atlanta, Ga., (1915). 



PHYSICAL PROPERTIES OF CARBON DIOXIDE 97 

Solubility of Carbon Dioxide in Water Solutions of Inorganic Com- 
pounds. Because of the large amount of data reported it is somewhat 
difficult for one to see at a glance what effect the presence of inorganic 
compounds may have on the solubility of carbon dioxide in water. In the 
tables following an attempt has been made to rearrange these results and 
in many cases to recalculate them to a common unit. In cases where the 

TABLE 46. The Solubility of Carbon Dioxide in Water at Various Temperatures in 
F. and Various Pressures in Ibs. per sq. in. Gage. 

Table shows the volume of carbon dioxide measured at 32 F. and 147 
Ibs./sq. in. which dissolves in one volume of water at the temperature and 
pressure indicated. 

(Calculated by Heath) 

Plbs./ t Temperature C. N 

sq.in. 32 36 40 44 48 55 60 65 70 75 80 85 90 

15 3.46 3.19 2.93 2.70 2.50 2.20 2.02 1.86 1.71 1.58 1.84 1.35 1.27 

20 4.04 3.73 3.42 3.15 2.92 2.57 2.36 2.17 2.00 1.84 1.69 1.58 1.48 

25 4.58 4.27 3.92 3.61 3.35 2.04 2.69 2.48 2.29 2.10 1.93 1.80 1.70 

30 5.21 4.81 4.41 4.06 3.77 3.31 3.03 2.80 2.58 2.37 2.18 2.03 1.91 

35 5.80 5.35 4.91 4.52 4.19 3.69 3.37 3.11 2.86 2.63 2.42 2.26 2.13 

40 6.37 5.89 5.39 4.97 4.61 4.05 3.71 3.42 3.15 2.89 2.67 2.49 2.34 

45 6.95 6.43 5.88 5.43 5.03 4.43 4.06 3.74 3.44 3.16 2.91 2.72 2.56 

50 7.53 6.95 6.36 5.89 5.45 4.80 4.40 4.05 3.73 3.42 3.16 2.94 2.77 

55 8.11 7.48 6.86 6.34 5.87 5.17 4.74 4.37 4.02 3.69 3.40 3.17 2.99 

00 8.71 8.02 7.35 6.79 6.29 5.53 5.08 4.68 4.31 3.95 3.64 3.39 3.20 

70 9.86 9.09 8.33 7.70 7.13 6.27 5.76 5.30 4.89 4.49 4.14 3.86 3.63 

80 11.02 10.17 9.31 8.61 7.98 7.00 6.43 5.92 5.46 5.02 4.62 4.31 4.06 

90 12.18 11.25 10.30 9.52 8.82 7.74 7.11 6.54 6.04 5.55 5.12 4.77 4.49 

100 13.34 12.33 11.29 10.43 9.66 8.40 7.79 7.18 6.62 6.08 5.60 5.22 4.91 

densities of the solutions were not reported in the original papers, an 
attempt has been made to supply them. In most cases such densities were 
obtained from the density tables of Hodgman and Lange. 151 The Bunsen 
absorption coefficient has been selected as the most useful unit for express- 
ing the solubility of the gas, while the concentration of the salt is, in gen- 
eral, given as moles per liter of solution. Exceptions to this have been 
made in a few cases, notably the data of Christoff who expresses his con- 
centrations in terms of normality. In some cases there is much uncertainty 
as to how he calculated this normality. In the data of Setschenow the 
absorption coefficient is based on the number of cc. of carbon dioxide 
measured at C. and 760 mm. pressure which dissolved in one cc. of a 
saturated solution of carbon dioxide. It will be noted that this coefficient 
may deviate slightly from the Bunsen coefficient which is based on one cc. 
of the solvent. There are reasons to believe, however, that this slight 
difference is much less than the error of measurements and these values 
have been listed as Bunsen absorption coefficients. These data have been 
tabulated in Table 47. 

m HodRman, C. D., and Lange, N. A., "Handbook of Chemistry and Physics." Chemical 
Rubber Publishing Co., Cleveland (1929). 



98 



CARBON DIOXIDE 



TABLE 47. Solubility of Carbon Dioxide in Water Solutions of Inorganic Compounds. 



Compound 


Temp. 
C 


Moles of comp. 
per liter sol. 


Density at 
fG* 


Absorption 
coeff. a 


Observer 


HC1 


15.0 


0.500 


1.007* 20 


0.989 


Geffcken 


ii 




1.000 


1.016* " 


0.975 


M 


ii 





2.000 


1.033* " 


0.948 


tt 


ii 


25.0 


0.500 


1.007* " 


0.738 


tt 


it 




1.000 


1.016* w 


0.732 


tt 


it 


<< 


2.000 


1.033* " 


0.728 


if 


HNO, 


15.0 


0.500 


1.015* " 


1.022 


it 


ii 




1.000 


1.032* " 


1.029 


ii 


ii 


tt 


2.000 


1.066* " 


1.042 


it 


ii 


25.0 


0.500 


1.015* " 


0.769 


ft 


ii 




1.000 


1.032* " 


0.781 


ft 


ii 


^ 


2.000 


1.066* " 


0.803 


f< 


H a SO 4 


15.0 


0.250 


1.015* " 


0.965 


tt 


ii 





0.500 


1.030* " 


0.927 


tt 


ii 


K 


1.000 


1.061* " 


0.869 


tt 


ii 





1.500 


1.091* " 


0.662 


n 


ii 





2.000 


1.120* " 


0.632 


tt 


ii 


15.5 


0.258 


1.015* " 


0.865 


tt 


ii 




0.526 


1.032* " 


0.728 


tt 


ii 





1.087 


1.066* " 


0.562 


tt 


ii 





2.323 


1.139* " 


0.509 


tt 


it 


tt 


3.727 


1.218* " 


0.507 


tt 


ii 





5.313 


1.303* " 


0.481 


tt 


ii 


ii 


6.182 


1.348* " 


0.489 


tt 


it 





11.49 


1.610* " 


0.619 


tt 


ft 


tt 


16.65 


1.814* " 


0.967 


tt 


ii 


20.0 


4.672 


1.267* " 


0.607 


tt 


4 


it 


9.521 


1.516* " 


0.670 


tt 


it 





17.88 


1.835* " 


0.925 


tt 


ii 


t 


17.96 


1.836* " 


0.926 


Bohr 


LiCl 


15.2 


0.394 





1.035 


Setschenow 


ii 




1.182 





0.808 


" 


ii 


ii 


2.957 





0.596 


" 


ii 


ii 


5.915 





0.497 


" 


ii 





11.82 





0.120 


" 


ii 


15.5 


1.000 




0.733 


Christoff 


NH 4 C1 


8.0 


1.233 


i.bii is 


1.023 


Mackenzie 


ii 


" 


1.707 


1.047 


1.000 


" 


ii 





2.505 


1.053 " 


0.922 


" 


ii 


10.0 


4.856 


1.072 


0.813 


" 


ii 


15.0 


1233 


1.021 


0.825 


Mackenzie 


ii 


ii 


1.707 


1.047 


0.791 


" 


a 





2.505 


1.053 


0.798 


" 


ii 


" 


4.856 


1.072 


0.738 


11 


ii 


15.2 


0.019 


1.000* 20 


1.013 


Setschenow 


ii 




0.187 


1.001* " 


0.985 


" 


ii 


ti 


0.965 


1.014* " 


0.941 


" 


ii 


" 


3.216 


1.047* " 


0.819 


" 


1C 


" 


4.822 


1.068* " 


0.770 


" 


II 


22.0 


1.233 


1.021 15 


0.718 


Mackenzie 


II 




1.707 


1.047 


0.702 


" 


II 


" 


2.505 


1.053 


0.684 


" 


II 


" 


4.856 


1.072 " 


0.600 


u 


(1 


25.0 


0.439 


1.005 25 


0.724 


Findlay and Shen 


ff 


" 


0.966 


1.013 " 


0.691 


u ii 


tf 


1C 


1.873 


1.022 


0.670 


u if 


II 


II 


3.J94 


1.045 " 


0.609 


ii if 



PHYSICAL PROPERTIES OF CARBON DIOXIDE 



99 



TABLE 47. (Continued) 


Compound 


Temp. 


Moles of comp. 
per liter sol. 


Density at Absorption 
*C* coeff.a 


Observer 


NH 4 NO, 


15.2 


0.035 


1.001+ 


17.5 


1.013 


Setschenow 


ii 


" 


0.140 


1.005+ 


" 


1.002 


" 


" 


" 


0.687 


1.023+ 


" 


0.989 


" 


11 


ii 


1261 


1.041+ 


" 


0.962 


" 


" 


" 


2.525 


1.080+ 


" 


0.911 


" 


11 


" 


5.051 


1.155+ 


" 


0.807 


" 


" 


" 


10.123 


1.297+ 





0.612 


" 


(NH,),SO. 


15.2 


0.546 


1.034+ 


20 


0.712 





" 


" 


1.092 


1.077+ 


11 


0.575 


" 


It 


15.5 


0.500 


1.032+ 


" 


0.737 


Christoff 


FeS0 4 (NH 4 ) 2 














S0 4 -6H 2 


25 


0242 


1.052 


25 


0.587 


Findlay and Shen 


" 


" 


0.261 


1.057 


* 


0.576 


it tt 


1C 


ii 


0.572 


1.124 





0.421 


^ u 


(NH 4 ) a 














Fe a (S0 4 ) 4 
24H a O 


15.5 


1.000 (N) 






0.668 


Christoff 


NH 4 HB 2 O 4 


15.5 


0.25 (N) 






5.18 (?) 


" 


NaCl 


0.0 


"1.170 


1.0554 


13.3* 


1.234 


Bohr 


" 


" 


3.407 


1.1308 


12.3 


0.678 


" 


" 


5.0 


1.170 


1.0554 


13.3 


1.024 


" 


" 


" 


3.407 


1.1308 


12.3 


0.577 


" 


it 


6.4 


1.253 


1.038 


15.0 


0.899 


Mackenzie 


" 





2.400 


1.080 


" 


0.633 


" 


" 


" 


3.344 


1.123 


* 


0.518 


" 


" 


" 


5.312 


1.195 


" 


0.347 


" 


" 


10.0 


1.170 


1.0554 


13.3 


0.875 


Bohr 


11 


" 


3.407 


1.1308 


12.3 


0.503 


" 


ii 


15.0 


1.170 


1.0554 


13.3 


0.755 


" 


" 


11 


1.253 


1.038 


15.0 


0.735 


Mackenzie 


" 


" 


2.400 


1.080 


" 


0.557 


" 


ii 


" 


3.344 


1.123 





0.431 


11 


ii 


i 


3.407 


1.1308 


12.3 


0.442 


Bohr 


" 


ii 


5.312 


1.195 


15.0 


0.297 


Mackenzie 


it 


15.2 


0.220 







0.978 


Setschenow 


ii 


ii 


1.094 






0.760 


1C 


ii 


u 


2.188 






0.580 


II 


" 


" 


3.282 








0.466 


" 


" 


15.5 


1.000 


. 




0.708 


Christoff 





20.0 


1.170 


1.0554 


13.3 


0.664 


Bohr 


ii 


" 


3.407 


1.1308 


12.3 


0.393 





ii 


22.0 


2.400 


1.080 


15.0 


0.482 


Mackenzie 


11 


" 


3.344 


1.123 


" 


0.389 


" 


11 


" 


5.312 


1.195 


" 


0.263 


" 


ii 


25.0 


1.170 


1.0554 


13.3 


0.583 


Bohr 


11 


" 


3.407 


1.1308 


12.3 


0.352 


" 


" 


30.0 


1.170 


1.0554 


13.3 


0.517 


" 


u 





3.407 


1.1308 


12.3 


0.319 


" 


" 


35.0 


1.170 


1.0554 


13.3 


0.460 


" 


tt 





3.407 


1.1308 


12.3 


0288 


11 


tt 


40.0 


1.170 


1.0554 


13.3 


0.414 


u 


u 


" 


3.407 


1.1308 


12.3 


0.268 


it 


" 


45.0 


1.170 


1.0554 


13.3 


0.370 





u 





3.407 


1.1308 


12.3 


0235 


" 


" 


50.0 


1.170 


1.0554 


13.3 


0.335 


ti 


ii 


1C 


3.407 


1.1308 


12.3 


0.215 


" 


11 


55.0 


1.170 


1.0554 


13.3 


0.305 


" 


ii 


" 


3.407 


1.1308 


12.3 


0.198 


" 


" 


60.0 




" 


" 


0.183 - 


" 



100 



CARBON DIOXIDE 
TABLE 47. (Continued) 



Compound 


Temp. 

c. 


Moles of comp. 
per liter sol. 


Density at 
*C* 


Absorption ^, 
coeff.a Observer 


NaBr 


152 


1.118 


1.086+ 


20.0 


0.775 


Setschenow 


ft 


If 


4.473 


1.338+ 


20.0 


0.362 


ft 


<i 


ff 


6.709 






0.221 


<t 


NaN0 8 


15.2 


1.102 


1.056+ 


2616 


0.835 


tt 


ft 


if 


1.543 


1.079+ 


ff 


0.762 


ft 


i< 


tt 


2.572 


1.130+ 


f< 


0.621 


tt 





ft 


5.145 


1.254+ 


it 


0.385 


t 


ft 


ft 


7.717 






0.244 


tt 


NaClO 3 


15.2 


2.192 





! ... 


0.625 


tt 


ft 


if 


3.288 







0.506 


tt 


<i 


ft 


6.576 






0.257 


4t 


Na a S0 4 


15.2 


0.100 


1.011+ 


20 


0.950 


ft 


*i 


ft 


0.668 


1.080+ 


ft 


0.620 


** 


<f 


ft 


2.000 


1.225+ 


it 


0.234 


it 


Na 4 B 4 O 7 


15.5 


0.025 (N) 







1.487 


Christoff 





ii 


0.125 (N) 







3.586 


ft 


K 


if 


0.250 (N) 







5.741 


it 


ff 


ff 


Sat. sol 






12.33 


tt 


ft 


tf 


" " -fcryst 








21.75 


ft 


NaBO a 


15.5 


0.250 


..... 




5.478 


it 


Na,PO 4 -12H 2 O 
Na 4 P 2 O 7 10H 2 O 


15.5 
15.5 


1.000 (N) 
1.000 (N) 





.... 


3.932 
5.709 


ff 


Na,P 4 O 13 
KC1 


15.5 
8.0 


1.000 (N) 
0.828 






0.472 
0.988 


tf 
Mackenzie 


1.021 


15 


ft 


it 


1.220 


1.053 


" 


0.918 


if 


ft 


ff 


1.732 


1.080 


if 


0.864 


<f 


K 


H 


4.674 


1.549 


ii 


0.688 


K 


fi 


15.0 


0500 






0.925 


Geffcken 


II 


if 


0'.828 


1.021 


15 


0.777 


Mackenzie 


ff 


ff 


1.000 






0.850 


Geffcken 


l( 


ft 


1.220 


1.053 


is" 


0.777 


Mackenzie 


If 


ft 


1.732 


1.080 


ff 


0.720 


tf 


ff 


tf 


4.674 


1.549 


ff 


0.571 


ct 


<f 


155 


1000 






0.818 


Christoff 


(( 


22.0 


0'.828 


1.021 


15 


0.670 


Mackenzie 


(I 


tt 


1.220 


1.053 


ft 


0.649 


it 


l< 


if 


1.732 


1.080 


ft 


0.597 


ft 


(4 


ff 


4.674 


1.549 


ft 


0.480 


ft 


<t 


25.0 


0.500 






0.695 


Geffcken 


(1 


ft 


0.614 


1.026 


25" 


0.686 


Findlay and Shen 


II 


ft 


1.000 


1.044 


ft 


0.642 


ff <f 


41 


ff 


1.000 


1.044+ 


ft 


0.641 


Geffcken 


KBr 


15.0 


0.500 


1.040+ 


20 


0.935 


ft 


If 


ft 


1.000 


1.082+ 


ft 


0.866 


fi 


(1 


15.2 


0.705 


1.058+ 


tf 


0.908 


Setschenow 


l< 


it 


1.409 


1.116+ 





0.819 


it 


41 


ft 


2.113 


1.173+ 


ft 


0.748 


ft 


14 


ft 


4.227 


1.343+ 


ft 


0.579 


ft 


14 


15.5 


1.000 


1.082+ 


ft 


0.863 


Christoff 


44 


25.0 


0.500 


1.040+ 


ft 


0.703 


Geffcken 


ff 


ft 


1.000 


1.082 


ft 


0.653 


ft 


KI 


15.0 


0.500 


1.045+ 


20 


0.940 


ft 


H 


ft 


1.000 


1.118+ 


ft 


0.875 


ft 


44 


15.2 


1.922 


1.227+ 


tt 


0.777 


Setschenow 


4( 


ff 


2.883 


1.340+ 


ti 


0.688 


ft 


If 


n 


5.767 






0.506 


ft 


ft 


15.5 


1.000 


1.118+ 


20 


0.812 


Christoff 


It 


25.0 


0.500 


1.045+ 


tf 


0.710 


Geffcken 



PHYSICAL PROPERTIES OF CARBON DIOXIDE 



101 



TABLE 47. (Continued) 



Compound 


Temp. 
C. 


VIolcs of comp. 
per liter sol. 


Density at 
fC* 


Msorptio 


n Observer 


KI 


25.0 


1.000 


1.118+ 20 


0.660 


Geffcken 


KNO 3 


15.0 


0.500 


1.029+ " 


0.953 


" 




" 


1.000 


1.050+ " 


0.897 


" 





15.2 


0.582 


1.034+ " 


0.959 


Setschenow 


tt 




1.162 


1.069+ " 


0.890 


" 


*t 





2.325 


1.137+ " 


0.781 


" 


tt 


15.5 


1.000 


1.050+ " 


0.830 


Christoff 


ii 


25.0 


0.500 


1.029+ " 


0.718 


Geffcken 





" 


1.000 


1.050 f " 


0.686 


" 


KHS0 4 


15.5 


0.66 (N) 




0.688 


Christoff 


" 


11 


2.00 (N) 


.... 


0.675 


" 


K 2 S0 4 


15.5 


0.66 (N) 




0.769 


" 


** 


" 


1.00 (N) 


.... 


0.676 


" 


K 2 A1 2 (S0 4 ) 4 - 


15.5 


1.00 (N) 




0.711 


it 


241 1 2 O 












K 2 HAsO 4 


15.5 


0.500 (N) 




0.749 


** 


KH 2 As a O 4 


15.5 


1.00 (N) 


..... .... 


0.548 


" 


KH 2 PO 4 


15.5 


1.00 (N) 




0.580 


11 


K 4 P 4 12 
KSCN 


15.5 
15.2 


1.00 (N) 
3.356 




0.830 
0.691 


Setschenow 




" 


5.032 




0.590 


* 








10.06 




0.387 




MgSO 4 


15.2 


0.220 


1.024* 20 


0.901 




1 


" 


0.660 


1.075+ " 


0.669 










1.320 


1.148+ " 


0.441 







" 


2.641 


1.280+ " 


0.188 







15.5 


0250 


1.028+ " 


0.816 


Christoff 


i 




0.500 


1.057+ " 


0.688 


it 





" 


1.000 


1.112+ " 


0.447 


" 








2.000 


1.217 4 " 


0.355 


" 


CaCl, 


8.0 


0.407 


1.036 15 


0.942 


Mackenzie 


" 


11 


0.542 


1.049 15 


0.855 


" 


< 





0.774 


1.068 


0.838 


" 








1.620 


1.139 


0.632 


" 


< 


16.25 


0.407 


1.036 


0.759 


it 







0.542 


1.049 


0.726 


'* 








0.774 


1.068 


0.674 


i 





ii 


1.620 


1.139 


0.520 


it 





22.0 


0.407 


1.036 


0.673 


" 





ii 


0.542 


1.049 


0.616 


it 








0.774 


1.068 


0.581 


ii 





ii 


1.620 


1.139 


0.471 


it 


" 


30.0 


0.407 


1.036 


0.596 


ii 


< 




0.542 


1.049 


0.527 


ii 


tt 


tt 


0.774 


1.068 


0.500 


ii 


tt 


it 


1.620 


1.139 


0.400 


ii 


Ca(NO.,) 2 


15.2 


0241 




0.923 


Setschenow 


CuSO 4 


15.5 


1.000 




0.507 


Christoff 


ZnSO, 


15.2 


0.237 


1.023+ 15 


0.903 


Setschenow 






0.475 


1.043+ " 


0.783 


< 








1.424 


1.126+ " 


0.474 


" 





ii 


2.850 


1.246+ " 


0.209 


u 





15.5 


1.000 


1.090+ " 


0.486 


Christoff 


RhCl 


15.0 


0.500 




0.937 


Geffcken 


ii 




1.000 





0.873 








25.0 


0.500 




0.701 


" 







1.000 




0.722 


" 


SrCl a 


8.0 


0.652 


1.087 15 


0.779 


Mackenzie 


" 


" 


0.868 


1.116 


0.737 


" 



102 



CARBON DIOXIDE 



TABLE 47. (Continued) 



Compound 
SrCl a 



CsCl 


Bad, 



Ba(NO,) 8 



Temp. 


Moles of comp. 


Density at 


C. 


per liter sol. 


fC* 


8.0 


1.310 


1.173 15 


" 


2.642 


1.343 


K25 


0.652 


1.087 " 





0.868 


1.116 


" 


1.310 


1.173 " 


" 


2.642 


1.343 


22.0 


0.652 


1.087 


" 


0.868 


1.116 


" 


1.310 


1.173 


M 


2.642 


1.343 


30.0 


0.652 


1.087 " 





0.868 


1.116 


" 


1.310 


1.173 


" 


2.642 


1.343 


15.0 


0.500 





25.0 


0.500 




8.0 


0.375 


1.068 15 


" 


0.511 


1.092 


11 


1.540 


1.273 


16.25 


0.375 


1.068 


" 


0.511 


1.092 


" 


0.766 


1.137 


11 


1.540 


1.273 


22.0 


0.375 


1.068 


" 


0.511 


1.092 


H 


0.766 


1.137 


" 


1.540 


1.273 " 


25.0 


0.115 


1.018 25 


M 


0.238 


1.040 


" 


0.334 


1.054 


" 


0.408 


1.070 


30.0 


0.375 


1.068 15 


* 


0.511 


1.092 


" 


0.766 


1.137 


" 


1.540 


1.273 " 


15.2 


0240 


. . . . 



Absorption Observer 

0.606 Mackenzie 

0285 

0.663 

0.586 

0.473 

0.245 

0.581 

0.507 

0.444 

0.247 

0.508 

0.539 

0367 

0.223 

0.954 Geffcken 

0.715 

0.969 Mackenzie 

1.021 

0.495 

0.744 

0.645 

0.618 

0.618 

0.680 

0.607 

0.524 

0.383 

0.723 Findlay and Sher 

0.679 

0.650 

0.619 

0.566 Mackenzie 

0.543 

0.467 

0.315 

0.922 Setschenow 



* Density values marked * were calculated from data given by Hodgman and Lange 
"Handbook of Physics and Chemistry" (1929). 

REFERENCES 

Listed in the order in which they anpear in Table 47. 

Geffcken, G M Z. physik. Chem., 49, 271. 296 (1904). 

Bohr, C M Ann. Physik. (3), 68, 503 (1899). 

Setschenow, Ann. chim. phys. (6), 25, 226 (1892). 

Christoff, A., Z. physik. Chem., 53, 321 (1905); 55, 627 (1906). 

Mackenzie, Ann. Physik. (2), 1, 450 (1877). 

Findlay, A., and Shen, B., J. Chem. Soc., 101, 1459-68 (1912). 

Solubility of Carbon Dioxide in Water Solutions of Carbon Com- 
pounds. Table 48 represents the data collected from various sources 
showing the solubility of carbon dioxide in solutions of carbon compounds. 
The method of listing these data is essentially the same as that used in 
Table 47. So much data are available on the solubility of carbon dioxide in 
alcohol solutions that they have been collected here as Table 49. It is of 
special interest to note the minimum solubility of carbon dioxide in solu- 



PHYSICAL PROPERTIES OF CARBON DIOXIDE 



103 



TABLE 48. Solubility of Carbon Dioxide in Water Solutions of Carbon Compounds. 



rp 

Compound 


C P> "r 5 DensityaU'C. 


Acetamide 


20.0 


0.500 




1.0005 


20 


Acetic acid 


" 


0.500 




1.0026 


" 


Antipyrine 


" 


0.500 




1.0134 


" 


Carbamide 


" 


0.500 




1.0072 


" 


Catechol 


" 


0.500 




1.0107 


" 


Citric acid 


15.2 


0.0624 




1.004 * 


" 






0.255 




1.018 * 


" 


ii n 


II 


0.515 




1.038 * 


" 





II 


1.030 




1.074 * 


ii 


n n 


II 


1.551 




1.110 * 


" 


ii ii 


II 


3.097 




1.215 * 


" 


Chloral hydrate 


15.0 


1.161 


17.7% 


1.0851* 


15 


ii ii 


" 


2.222 


31.6 


1.1631* 


" 


ii n 





2.795 


38.3 


1.2044* 


" 


i ii 





3.857 


49.8 


1.2808* 


" 


i ii 





4.603 


57.1 


1.3333* 


" 


n ii 


" 


5.923 


68.8 


1.4238* 


' 


n ii 


" 


7.263 


79.4 


1.5132* 


11 


n it 


25.0 


0.307 




1.019 


25 


ii ii 


" 


0512 




1.041 


" 


Dextrose 


20.0 


0.500 




1.0328 


20 


Glycerol 


15.0 


3.013 


26.11% 


1.0625* 


" 


" 


" 


5.149 


13.72 


1.1094* 


*' 


" 


" 


7.824 


62.14 


1.1591* 


" 


" 


" 


10.15 


77.75 


1.2018* 


" 


" 


ii 


12.18 


90.74 


1.2367* 


ii 


" 


ii 


13.57 


99.26 


1.2590* 


ii 


Glycine 


20.0 


0.500 




1.0141 


" 


Mannitol 


20.0 


0.500 




1.0303 


ii 


n Propyl alcohol 


20.0 


0.500 




0.9939 





Pyrogallol 


20.0 


0.500 




1.0172 


" 


guinol 


20.0 


0.500 




1.0095 


it 


esorcinol 


20.0 


0.500 




1.0096 


< 


Sucrose 


15.5 


0.100 








" 


" 


0.500 








" 


" 


1.000 








11 


20.0 


0.125 




1.0152 


20 


" 


ii 


0.250 




1.0313 




11 


ii 


0.500 




1.0637 


" 


" 


" 


1.000 




1.1281 


" 


it 


25.0 


0.077 




1.009 


25 


" 


** 


0.151 




1.018 





" 


M 


0.283 




1.038 


" 


" 





0.360 




1.051 





Thiocarbamide 


20.0 


0.500 




1.0092 


20 


Urethane 


20.0 


0.500 




1.0037 





0.879 
0.868 
0.859 
0.864 
0.868 
1.007 
0.975 
0.950 
0.893 
0.841 
0.719 
0.885 
0.803 
0.781 
0.760 
0.765 
0.797 
0.903 
0.815 
0.795 
0.792 
0.785 
0.639 
0.511 
0.454 
0.404 
0.410 
0.843 
0.782 
0.869 
0.853 
0.887 
0.901 
0.826 
0.735 
0.628 
0.846 
0.815 
0.756 
0.649 
0.745 
0.731 
0.702 
0.681 
0.859 
0.869 



Observer 

Usher 
ii 

n 

ii 
n 

Setschenow 
n 

n 
ii 
n 
ii 

von Hammel 
n 

ii 
ii 
i 
ii 
ii 

Findlay and Shen 

Usher 

von Hammel 
ii 

ii 
ii 
it 
ii 

Usher 
ii 

ii 
n 
n 
it 

Christoff 
ii 

ii 

Usher 
ii 

ii 
ii 

Findlay and Shen 
n ii 

ii n 

ii ii 

Usher 



Note. Density values for chloral hydrate were calculated by means of the equation found 
in the International Critical Tables which may be put in the following form: 

rf-.99913 f .004455 ^+.00002198 PJ+. 00000004366 /> x 8 

where /> is the per cent of chlorol hydrate in the solution. Other density values marked + were 
calculated from data given by Hodgman and Lange "Handbook of Physics and Chemistry." (1929). 

REFERENCES 

Usher, F. L., /. Ckem. Soc., 97, 66-78 (1910). 

Setschenow, Ann. chim. phys. (6), 25, 226 (1892). 

von Hammel, A., Z. physik. Chcm., 90, 121 (1915). 

Christoff , A., Z. physik. Chcm., 53, 321 (1905); 55, 627 (1906). 

Findlay, A. and Shen, B., /. Chcm. Soc., 101, 1459-68 (1912). 



104 



CARBON DIOXIDE 



tions containing about 28 per cent of alcohol. This phenomenon has also 
been observed by other investigators, for example Lubarsch. 152 

The Solubility of Carbon Dioxide in Organic Solvents. In Table 50 
are given the solubility data of Just 1 showing the solubility of carbon 



TABLE 49. Solubility of Carbon Dioxide in Ethyl Alcohol Solutions. 



Temp. 
C 

-78 



-65 
-59 

tt 

-20 

tt 

-10 


ff 

+ 10 
20 



22.4 

20 

17 

19.1 

18.8 

16.0 

19.0 

25 



40 
45 
30 



Pressure 

ofCO 2 Density at o temp, 
mm. of Hg. C. 

50 0.872 -78/4 
100 
200 
400 
700 
760 



% Alcohol Absorption 
by wt. coeff. a 



100 
200 
400 
700 



760 



737 

745 

747 

836 

937 

942 

1073 

1083 

1090 

1338 

1357 

1360 



760 



.856 



0.998 
0.969 
0.960 
0.956 
0.935 
0.922 
0.870 
0.835 
0.795 

6.9931 
0.9929 
0.9834 
0.9931 
0.9929 
0.9834 
0.9931 
0.9929 
0.9834 
0.9931 
0.9929 
0.9834 



-59/4 



20 



20 

17 

19.1 

18.8 

16 

19 

25/15 



Observer 



Stern 



93.30 

97.53 
100.9 

107.9 

120.8 

99.0 38.41 Bohr 

98.7 39.89 

34.97 Stern 

35.09 

36.25 

37.79 

99.0 7.51 Bohr 

98.7 7.25 

99.0 5.75 

98.7 5.43 

99.0 4.44 

98.7 4.35 

99.0 3.57 

99.0 2.98 

1.07 0.861 Miiller 

22.76 0.841 

28.46 0.792 

31.17 0.801 

42.15 0.877 

49.0 0.982 

71.1 1.293 
85.3 1.974 
99.7 2.719 

99.0 2.76 Bohr 

2.97 0.721 Findlay and Shen 
3.03 0.731 

8.98 0.708 

2.97 0.819 
3.03 0.921 

8.98 0.890 

2.97 1.049 
3.03 1.061 

8.98 1.031 

2.97 1.308 
3.03 1.328 

8.98 1.292 

99.0 2.57 Bohr 

99.0 2.20 

99.0 2.01 



REFERENCES 

Stern, Otto, Z. physik. Chem., 81. 468 (1912-13). 
Bohr, C., Wicd. Ann. Physik. (4), 1, 247 (1900). 
Miiller, O., Wicd. Ann. Physik. (3), 37, 24-43 (1889). 
Findlay, A. f and Shen, B.. J. Chcm. Soc., (London), 99, 1313 (1911). 

1M Lubarsch, Ann. Physik. (2), 37, 525 (1889). 
"'Just, G. f Z. physik. Chcm., 37, 342-67 (1901)). 



PHYSICAL PROPERTIES OF CARBON DIOXIDE 



105 



TABLE SO. Solubility of Carbon Dioxide in Certain Organic Solvents. 

Solubility expressed in terms of the Ostwald solubility coefficient /. 

(Data by Just) 



Solvent 
Water 


8256 


/20 


/ 


Solvent 
Benzene 


2.425 


Glycerol 


0.0302 






Amylbromide . . . 


2.455 


Carbon disulfide. 
lodobenzene 
Aniline 


0.8699 
1.301 
1324 


0.8888 
1.371 
1 434 


0.9446 
1.440 
1.531 


Nitrobenzene . . . 
Propyl Alcohol.. 
Carvol 


2.456 
2.498 
2.498 


o-Toluidine 


1.381 


1.473 


1.539 


Ethyl Alcohol 




m-Toluidine .... 


1.436 


1.581 


1.730 


(97%) 


2.706 


Eugenol 


1.539 


1653 


1 762 


B en z aldehyde . 


2841 


Benzene Trichlo- 
ride 


1.643 






Amylchloride . . . 
Isobutyl chloride . 


2.910 
3.105 


Cumol 


1782 


1 879 


1978 


Chloroform 


3.430 


Carven 


1 802 


1 921 


2030 


Butyric Acid 


3478 


Dichlorhydrine. . 
Amyl Alcohol . . 


1.810 
1.831 


1.917 
1.941 


2.034 
2.058 


Ethylene Chloride 
Pyridine 


3.525 
3.656 


Bromobenzene . . 
Isobutyl Alcohol. 
Benzylchloride .. 
Metoxylol 


1.842 
1.849 
1.938 
2090 


1.964 
1.964 
2.072 
2216 


2.092 
2.088 
2.180 
2346 


Methyl Alcohol . 
Amyl formate ... 
Propionic Acid . . 
Amyl Acetate 


3.837 
4.026 
4.078 
4119 


Ethylcnebromide . 
Chlorobenzcne . . 


2.157 
2.265 


2.294 
2.420 


2.424 
2.581 


Acetic Acid (gla- 
cial) 


4.679 


Carbontctrachlo- 
ride 


2.294 


250? 


9 603 


Isobutyl Acetate. 
Acetic Anhvdndc 


4.691 
5 >06 


Propylenebromidc 


2.301 


2.453 


2.586 


Acetone 


6.295 


Toluene 


2.305 


2.426 


2.557 


Mpfhvl Acetate.. 


6.494 



2.540 2.710 

2.638 2.803 

2.655 2.845 

2.690 2.914 



2.923 
3.057 
3.127 
3.388 
3.681 
3.767 
3.795 
3.862 
4.205 
4.329 
4.407 
4.411 

5.129 
4.968 
5.720 
6.921 



3.130 
3.304 
3.363 
3.659 
3.956 
4.084 
4.061 
4.291 
4.606 
4.646 
4.787 
4.850 

5.614 
6218 



dioxide in various organic solvents at three different temperatures. For 
many years these were the only data available for such solubility measure- 
ments and much theoretical discussion has hinged on them. More recently 
Kunerth 154 has extended this field with some carefully worked out experi- 
ments covering a greater temperature range. The results of these deter- 
minations are listed in Table 51. Table 52 shows the results of Stern 1 * 3 



TABLE 51. The Solubility of Carbon Dioxide in Certain Organic Solvents. 

Solubility expressed in terms of the Oslwald solubility coefficient /. 

(Data by Kunerth) 



Compound 



18 20 



Water 

Acetone 

Acetic Acid 5.40 

Pyridine 3.95 

Methyl Alcohol .. 3.63 
Ethyl Alcohol.... 2.95 
Benzaldehyde .... 3.06 

Aniline 

Amyl Acetate ... 4.79 
Ethylene Bromide 2.32 

Isoamyl Alcohol 

Chloroform 3.83 



22 



Temperature C. 
24 26 28 30 



32 34 36 



0.900 


0.872 


0.836 


0.800 


0.765 




6.98 


6.76 


6.55 


6.22 


5.88 


5.49 


5.23 


5.07 


4.91 


4.73 


4.57 


4.41 


3.85 


3.75 


3.63 


3.53 


3.45 


3.33 


3.57 


3.51 


3.44 


3.37 


3.28 


3.19 


2.87 


2.80 


2.73 


2.66 


2.58 


2.48 


2.99 


2.90 


2.80 


2.73 


2.66 


2.58 


1.38 


1.35 


1.32 


1.29 


1.25 


1.22 


4.65 


4.55 


4.44 


4.35 


4.24 


4.14 


2.27 


2.22 


2.16 


2.12 


2.07 


2.03 


1.91 


1.88 


1.85 


1.81 


1.76 


1.72 


3.71 


3.60 


3.50 


3.39 


3.26 


3.11 



0.693 

5.08 

4.25 

3.25 

3.09 

2.41 

2.52 

1.21 

4.10 

1.97 

1.69 

2.94 



0.656 

4.66 

4.12 

3.13 

2.97 

2.31 

2.46 

1.19 

4.02 

1.92 

1.67 

2.81 



4.00 
3.03 



239 
1.17 

i.86 
2.68 



M Kunerth, William, Phys. Rev., 19, 512-24 (1922). 
Stern, Otto, Z. physik. Chcm., 81, 468 (1912-13). 



106 CARBON DIOXIDE 

TABLE 52. Solubility of Carbon Dioxide in Organic Solvents at Low 
Temperatures and Pressures. 

Expressed in terms of the Ostwald solubility expression /. 
(Data by Stern) 

-Solvents- 



T o e p p> in mm. Methyl A*miA Ei W Methyl 



^' ofHg. alcohol * acetate acetate 

-78 50 120.5 196.6 177.5 224.1 

100 119.6 198.1 177.1 224.3 

200 120.1 201.5 179.2 223.1 

400 122.2 208.8 183.2 225.6 

700 126.8 

-59 100 42.5 67.2 65.6 75.8 

200 42.7 68.0 65.3 77.1 

400 43.1 72.8 66.7 77.6 

700 43.35 72.8 69.7 79.0 

Densities at -78/4 0.884 0.900 1.017 1.056 

Densities at -59/4 0.866 0.879 0.994 1.032 

at very low temperatures. Sander 150 has also determined the solubility 
of carbon dioxide in various organic solvents to pressures as high as 130 
kg. per sq. cm. Inasmuch as these solubility data were made with such 
very small volumes of solvent (0.08 cc. in one case) not much confidence 
can be placed on them. 

Supersaturation of Carbon Dioxide in Liquids. This phenomenon so 
common to solutions of solids in liquids is also displayed to a certain extent 
in solutions of gases in liquids. To the bottling industry the supersatura- 
tion of carbon dioxide in beverages is of special importance and a gas which 
fails to do this properly is said to be "wild". The bottler well knows that 
"wildness" is clue to impurities, usually air, in the carbon dioxide used for 
carbonating the beverage. As will be shown later there are other causes 
than gaseous impurities for the failure of a gas to produce a properly super- 
saturated solution. 

In agitated solutions of gases the rate of desaturation follows the well 
known logarithmic law and this rate is therefore proportional to the con- 
centration of the gas in the solution. 157 It is also true that this logarithmic 
law applies equally well to the process of absorption of gases in liquids. 
Furthermore Bohr 158 has shown that the ratio of the volume of gas which 
passes into solution through unit area in unit time (invasion coefficient) to 
the volume of gas which similarly passes out of solution (evasion coeffi- 
cient) is constant, and equal to the absorption coefficient. 

In the case of certain unagitated solutions, however, the rate of gas 
evolution may be very irregular. Findlay and King 150 observed that on 
reducing the pressure of carbon dioxide gas above a solution to atmospheric 
conditions, a period of quiescence ensues, during which no gas escapes from 

Sander, W., Z. physik. Chcm., 78, 513-49 (1911). 

Carlson. T., J. chim. phys. t 9, 235 (1911). 

1M Bohr f C. f Ann. Physik. (3), 68, 500 (1899). 

1M Findlay, A., and King, (J. f J. Chem. Soc. t 103, 1170-93 (1913). 



PHYSICAL PROPERTIES OF CARBON DIOXIDE 107 

the supersaturated solution. In this condition the solution is very sensitive 
to mechanical disturbance and even a slight jar is sufficient to cause a rapid 
evolution of gas. It was also found that particles of solid in the solution as 
well as grease or dirt on the walls of the vessel prevented this period of 
quiescence. Moreover, it was discovered that this period did not endure 
indefinitely, after a certain time the evolution of gas started spontaneously 
and a rapid evolution of gas took place which gradually diminished to a 
certain point, when another rapid evolution took place and this phenomenon 
continued until equilibrium was finally established. Solutions of dextrin 
and solutions of gelatin showed a well marked period of quiescence while 
solutions of peptone and ferric hydroxide liberated the carbon dioxide 
immediately on reduction of pressure. 

In an attempt to find some basis of comparison for the degree of super- 
saturation of carbon dioxide in various types -of water solutions these 
investigators developed the following equation : 



(36) 



where k is a constant, t is time in seconds and v the volume of gas evolved 
in t seconds while V is the total volume evolved. While this equation is of 
no special importance from a theoretical point of view the average values 
of k do show to a certain extent the relative rates of clesaturation of the 
various solutions. As far as the authors are aware no better method of 

TABLE 53. The Super saturation of Carbon Dioxide in Water Solutions 
of Various Substances. 

(Data by Findlay and King) 



Solvent Solute -* (Average) 



Water ............................. 0.0665 

Potassium chloride .... 60.000 .0546 

Gelatin ............... 0.242 .0904 

............... 0.281 .1245 

............... 0.502 .1504 

............... 30.010 2335 

Dextrine ............. 10.010 .0657 

............. 30.000 .0572 

............. 125.100 .0672 

Starch ............... 30.000 .0367 

Peptone .............. 7.580 .0157 

Ferric hydroxide ..... 3.767 .0615 

..... 13.530 .0671 

expression has been devised up to the present time and therefore values 
of k have been listed in Table 53 showing the various solutions studied by 
Findlay and King. It should be noted that the values of k are averages 
taken from tables in which they are far from constant. 

In a later research Findlay and King 160 studied in more detail the super- 
saturation of carbon dioxide in water solutions of gelatin and starch and 

1M Findlay, A., and King, G., /. Chftn. Soc. t 105, 1297-1303 (1914). 



108 CARBON DIOXIDE 

concerned themselves primarily with the changes that took place with differ- 
ent methods of treating the solution. More recently, Findlay and Howell, 101 
studied the rate of evolution of carbon dioxide from water solutions in the 
presence of colloids. In the case of starch and dextrin the velocity 
coefficient was greater than for pure water solutions of carbon dioxide and 
in the case of ferric hydroxide and gelatin the coefficient was smaller. 

Metschl 162 investigated the supersaturation of carbon dioxide in water 
and alcohol solutions and found that within the pressure limits of 1 to 5 
atmospheres of saturation pressure the degree of supersaturation was 
proportional to the saturation pressure. He found that V/P for water 
solutions of carbon dioxide was 0.0541 (average) and for alcohol solutions 
(98 per cent ethyl alcohol) it was 0.157. V is the volume of carbon 
dioxide measured under standard conditions, shaken out of the solution 
after the pressure had been reduced from P (measured in mm. of Hg) 
to one atmosphere. 

Kenrick, Wismer and Wyatt 103 in the same year published results 
obtained in a scries of researches on supersaturation. Pressures used by 
these investigators for the saturation of water with carbon dioxide were 
as high as 35 atmos. and it was found that even with these high pressures 
the solution could be reduced to one atmosphere without the formation of 
gas bubbles. It was also noted that an increase in the temperature of the 
solution favored the formation of gas bubbles but that a long heating of the 
tube containing the solution at a high pressure favored supersaturation. 

Liquid Carbon Dioxide as a Solvent. The behavior of liquid carbon 
dioxide as a solvent was first investigated by Gore. 104 His work was 
necessarily qualitative in nature and was carried out by the simple process 
of allowing the solute to remain in contact with the liquid carbon dioxide 
in a tube over night at room temperature. He observed that naphthalene 
and camphor showed the greatest solubility, that yellow phosphorus and 
iodine showed only slight solubility, whereas other compounds (organic 
and inorganic salts) seemed to have no solubility. The beautifully colored 
solution of iodine in liquid carbon dioxide attracted the attention of several 
other investigators some of whom reported the results of solubility 
studies. 105 Hannay 100 found that silicates, phosphates and borates became 
dissolved to a certain extent in liquid carbon dioxide at high temperatures 
and pressures. Finally Dolter 107 reported that silicates were soluble in 
liquid carbon dioxide in the presence of water. 

A study of binary mixtures of carbon dioxide with liquids and gases 
has been made by Dewar 108 who investigated carbon disulfide, chloroform 

101 Findlay, A., and Unwell, O. R., /. Chrm. .SV>r., 121, 1046 (1922). 

1W Metschl, John, /. Phys. Oinn., 28, 417-38 (1924). 

101 Kenrick, F. B., Wismer, K. L., and Wyatt, K. S. f /. Phys. CJicm., 28, 1308-15 (1924). 

M *C.ore, G., Proc. Rov. Soc. (London), 11, 85 (1861); Chem. News, 3, 2990 (1861); PJiil. Man. 
(4), 22, 485 (1861). 

"* Barqiierel, Comfit, rend., 75, 1271 (1872). Cailletct, L. P., Comfit, rend., 92, 840 (1881); 
108, 1280 (1889). Villard, P., Ann. chim. fihys. (7), 10, 387 (1897). 

1M Hannay, J. B., Proc. Roy. Soc. (London), 32, 407 (1881). 

lfl7 Dolter, C., "Neues Jahrburh f. Mineralo^ie, GeoloRie und 'Palaontologie," I, 118 (1890). 

Dewar, J., Proc. Roy. Soc. (London), 30, 538 (1880). 



PHYSICAL PROPERTIES OF CARBON DIOXIDE 109 

and benzene and Kuenen 160 who studied the critical phenomenon of mixing 
of acetylene, ethane, and methyl chloride. 

Somewhat later Biichner made a rather exhaustive phase study of 
liquid carbon dioxide and various compounds mostly of the organic type. 
His summary of the information obtained up to that time is interesting. 
The classes of substances which had been found to be insoluble were : 

Halogen salts: CaCl 2 , HgCl 2 , HgI 2 , NaCI, KBr, KI. 

Sul fates: CuSO 4 , FeSO 4 . 

Nitrates : AgNO 3 . 

Carbonates: CaCO 3 , Na 2 CO 3 . 

Elements: C, Si, Al, S, K, Na. 

Additional: As 2 O 3 , SiO 2 , K 2 Sil%, Ca 3 P 2 , HPO 3 , Hg(CN) 2 , phosphorus sulfidc 
and sodium phosphide. 

Those substances having a slight solubility were: PCI-,, AsBr 3 , SbBr 3 , 
P (yellow), I and Br. Biichner conducted an elaborate research in which 
he investigated the phase relations in a large number of systems containing 
liquid carljon dioxide and various organic compounds. The results of this 
study are summarized in three classes : First those substances which were 
completely miscible in the liquid state such as p-dichlorbenzene, camphor, 
carbon disulfide, ether, pcntane, amylene, acetone, benzene and xylene. 
Second, those having a very limited solubility such as naphthalene, phen- 
anthrene, iodoform, p-dibrombcnzene, borneol, substituted phenols such as 
nitrophenol, p-chlornitrobenzene, 1.2.3. and 1.3.2. dichloronitrobenzenc, 
succinic acid anhydride, uric acid, benzamide, etc. Third, those having a 
limited solubility of liquids such as propyl-, butyl-, and isobutyl alcohols 
and bromoform which produce miscible solutions on warming. 

The only strictly quantitative measurements of the solubility of solid 
solutes in liquid carbon dioxide were made by Quinn 171 who made a series 
of determinations using naphthalene and iodine as solutes. The results 
reported in terms of mole per cent of the solute at different temperatures 
for naphthalene are as follows : 

Temp. C 25 20 10 -21 

Mole % C 10 H 0.698 0.662 0.511 0.372 0.180 

and the results obtained when iodine was used as solute are : 

Temp. C 25 20 10 -11.4 -21 

Mole % I 2 0.0361 0.0305 0.0207 0.0136 0.00753 0.00405 

Another investigation made by the same author 172 was designed to deter- 
mine the solubility of lubricating oil in liquid carbon dioxide. These deter- 
minations were of importance from the point of view of compressor lubri- 
cation and especially in refrigeration systems where carbon dioxide was 
used as the refrigerant. The results obtained were as follows : 

Temp. C 25 20 10 -20 

Cms. oil per 100 gms. CO 2 .... 0.718 0.843 0.904 0.800 0.388 

v. Kuenen, Phil. Mac,. (5), 44, 174 (1897). 
1TO Buchner, E. H., Z. physik. Chcm., 54, 665-88 (1905-6). 
* n Quinn, E. L., 7. Am. Cficm. Soc., 50 672 (1928). 
" a Quinn, E. L., Ind. Eng. Chcm., 20, 735-40 (1928). 



110 



CARBON DIOXIDE 



One of the most interesting things concerning these data is the way the 
solubility of the oil reaches a maximum in the neighborhood of 10 C. 
This fact is shown more clearly in Figure 23 where the solubility curve has 
been plotted together with the density curves of the solvent and the solute. 
As is easily seen the maximum solubility takes place at the point where the 
densities of the components of the mixture are equal to each other. It 
should also be noted that at this temperature if liquid carbon dioxide and 
oil are sealed in a glass tube the position of the two non-miscible liquids 
change, that is to say, while at ordinary temperatures liquid carbon dioxide 
floats on the 'surface of the oil when the temperature is brought below 10 
C. the oil rises to the top of the mixture. This change in position is most 
interesting to watch while the temperature of the tube is slowly lowered. 



1 







V 










~ 5 ! 

-r 
l 



FIGURE 23. 

Solubility of Lubricating 
Oil in Liquid Carbon Diox- 
ide. 



!?? 

Temperature *C. 

The solubility of glycerol in liquid carbon dioxide was also treated in 
the investigation mentioned above. It was found that the solubility of 
glycerol was so small (less than 0.05 per cent) that no quantitative measure- 
ments were possible under the conditions of the investigation. 

The solubility of water in liquid carbon dioxide was investigated by 
Lowry and Erickson 173 who found the solubility less than 0.05 weight per 
cent over a temperature range from 5.8 C. to 22.9 C. 

A very complete and carefully worked out investigation of the solubility 
relations between liquid carbon dioxide and various liquids was made by 

M> Lowry, H. H. f and Erickson, W. R., /. Am. Chem. Soc., 49, 2729-34 (1927). 



PHYSICAL PROPERTIES OF CARBON DIOXIDE 111 

Thid and Schulte. 174 The binary system ethyl ether-carbon dioxide was 
considered in detail and the results obtained by an analysis of the liquid and 
gaseous phases after equilibrium had been established were as follows : 

Temp. C -78.6 -63.7 

ether 52.6 72.9 

CO, 47.4 27.1 

% ether 065 .25 

Phase \Mole % Co, 99.935 99.75 



Liquid / Mole 
Phase IMolc 



-23.8 

93.3 
6.7 

6.1 
93.9 



0.0 +15.2 
97.7 98.6 



2.3 

23.8 
762 



1.4 

45.4 
54.6 



4!A 


















^^ 


A 












^^ 


^ 


**~ 




\ 


to 


_. -40 








f ,> 


/* 


^^ 














^ 


y* 
















& 


f 














1 


A' 

J 


7 
















/ 


t ** 

D 

+ 

If 10 


/ 














' 




/ 


/ 
















II 




H.-44 

1 


' 














{ 

t 


V 




1 












u 


fy 




















V 

/ 


/ 
















^ 


X' 




















\ 


r 

UjA 










* 


ole 


% Ethir 




^ 






"% ; 

100 1 

M 

FIGURE 24. 
in the Carbon 


9 6O 40 20 ^ 

ole f* CO* 

t x Diagram for Solid, Liquid and Ga 
Dioxide-Ether System. 



In order to make a rather complete t-x diagram these investigators also 
determined the solubility of solid carbon dioxide in ether with the results 
shown below : 



Temp. C 

Mole % ether 
Mole % CO, . 



-83.5 
54.6 
45.4 



-92.5 
63.4 
36.6 



-98.0 
69.4 
30.6 



"Thiel, A., and Schulte, E., Z. physik. Chem., 96, 328 (1920). 



112 



CARBON DIOXIDE 



From these data a most interesting t-x diagram can be constructed and such 
a diagram is given as Figure 24 where the total pressure of the system is 
750 mm. 

TABLE 54. Equilibrium Systems of Solid Carbon Dioxide with Various Solvents 

(at 750 mm.). 

(Data by Thiel and Schulte) 
Equilibrium 



System 



Vapor phase 



Liquid phase 



temperature 
-78.6 

-78.65 
-78.64 
-78.78 
-79.44 
-82.11 



In Table 54 have been tabulated the results obtained by Thicl and 
Schulte on six equilibrium systems in which solid carbon dioxide was used. 

Of interest at this point is the process of Auerbach 17 '"' for fractionating 
oils in which liquid carbon dioxide is used as a solvent for certain fractions 
of oil. No commercial applications of the process are made at present. 



1 


Ethyl ether 
Carbon dioxide 


2 


Ethyl chloride 
Carbon dioxide 


3 


Sulfur dioxide 
Carbon dioxide 


4 


Methyl ether 
Carbon dioxide 


5 


Chlorine 
Carbon dioxide 


6 


Hydrogen sulfidc 
Carbon dioxide 



0.065 mole % 
99.935 mole % 


52.6 mole % 
47.4 mole % 


0.30 mole % 
99.70 mole % 


67.8 mole % 
32.2 mole % 


0.28 mole % 
99.72 mole % 


66.4 mole % 
33.6 mole % 


1.35 mole % 
98.65 mole % 


39.8 mole % 
60.2 mole % 


6.8 mole % 
93.2 mole % 


17.5 mole % 
82.5 mole % 


24.7 mole % 
75.3 mole % 


74.6 mole % 
25.4 mole % 



Auerbach, E. B., U. S. -Patent 1,805,751, May 19 (1931). 



Chapter IV 
Chemical Properties of Carbon Dioxide 

Chemically carbon dioxide is not an active compound and reactions 
between dry carbon dioxide and other compounds and elements can, in 
general, be promoted only at high temperatures. In water solutions, how- 
ever, the situation is quite different. Because of the acid properties of the 
solution many reactions take place spontaneously and some of them are of 
considerable geological importance. It will be the purpose of this chapter 
to consider many of these acid reactions and to deal also with some 
reactions taking place with the dry gas. 

Action of Carbon Dioxide on Water. The formation of a definite 
hydrate of carbon dioxide, having the composition CO 2 .8H 2 O was first 
observed by Wroblewsky. 1 He obtained the hydrate as an unstable solid on 
the side of a tube in which carbon dioxide under pressure of 45 atmos- 
pheres had been kept in contact with water at C. and after the pressure 
of the gas was decreased to 12.3 atmospheres. The solid so obtained was 
stable only when the temperature was kept -low and the gas pressure high. 
Villarcl 2 confirmed the formation of this hydrate but his method of analysis 
seemed to indicate that its composition was CO 2 .6H 2 O. The decomposition 
pressure of the hydrate was determined by both Villard and Wroblewsky 
and their results check in a most remarkable manner as will be seen in the 
following : 

Temp. C -6 0.48 2.7 3.6 5.3 6.1 6.3 6.9 10.0 

P in atm. Wroblewsky .. 12.3 16.7 17.9 21.8 23.3 26.1 

P in atm. Villard 6.5 12.2 12.7 16.7 17.9 21.8 23.3 26.1 44.3 

Later Hempel and Seidel 3 sealed a weighed quantity of solid carbon dioxide 
and water in a tube, and found that after the solid had melted, two liquid 
layers were formed. On cooling this system, crystals were produced which 
had a melting point of 8 C. An analysis of these crystals showed them to 
have a composition of either CO 2 .8H 2 O or CO 2 .9H 2 O. The former degree 
of hydration checks the results obtained by Wroblewsky and it may be 
'safely assumed that the correct formula is CO 2 .8H 2 O. 

The density of the octohydrate of carbon dioxide is not known but 
Wroblewsky noticed that it was greater than the density of water saturated 
with CO 2 . The heat of formation of CO 2 .8H 2 O was found by Villard to 
be 14.9 calories. 

v. Wroblewsky, S. t Wicd. Ann., 17. 103 (1892); Compt. rend., 94, 212 (1882). 
a Villard, P., Compt. rend., 119, 368 (1894); Ann. chim. phys. (7), 11, 355 (1897). 
Hempel. W., and Seidel, J.. Ber., 31, 2997 (1898). 

113 



114 CARBON DIOXIDE 

Carbonic Acid. The hydrate CO 2 .H 2 O or more correctly H 2 CO 3 is 
now quite generally recognized as a well-defined compound although it has 
never been isolated in the free state. Under ordinary conditions this com- 
pound, called metacarbonic acid, has weak acid properties. It may, how- 
ever, be considered a hydroxy derivative of formic acid and because of this 
it is to be expected it would have fairly strong acid properties. Recently 
numerous studies of the system carbon dioxide and water have shown this 
to be the case, at least from the point of view that carbonic acid is a highly 
dissociated compound in water solutions. 

It is also reasonable to expect the occurrence of the ortho form of 
carbonic acid, having the formula CO2.2HoO or H 4 CO4. Wilke 4 pointed 
out its probable existence but practically all the evidence we have for this 
lies in the fact that certain orthocarbonates, for example, ethyl orthocar- 
bonate C (OC2H r ,)4, are well known to students of organic chemistry. 

When carbon dioxide dissolves in water an interesting equilibrium is set 
up between the various molecules and the ions produced from them. One 
may write as one of the equations for this reaction the following : 

CO, (dissolved) +H a O *5 H 2 CO, *=* H*+HCO.- * 2H++CO,-. 

The carbon dioxide in solution is also in equilibrium with the undissolvecl 
carbon dioxide in the gaseous phase of the system, therefore another factor 
enters into the reaction. The conditions necessary to force this reaction 
either to the right or to the left are at once apparent and it might be men- 
tioned that when sufficient pressure of carbon dioxide is maintained over 
the solution it is possible to increase the hydrogen-ion concentration to a 
point where carbonic acid may take part in certain industrial operations. 

It may be profitable now for one to consider the above reaction step 
by step and to bring to light at least a few of the numerous researches 
concerning it. 

The first factor, that is, the solution of carbon dioxide in water, has 
been treated quite fully under the subjects of absorption and solubility. It 
might be mentioned again, however, that solutions of carbon dioxide obey 
Henry's law quite satisfactorily at moderate temperatures and low 
pressures. Morgan and Maass 5 have determined the value of Henry's law 

partial pressure of CO a in mm. of Hg 
mole fraction of CO 2 

constant K H where to be 0.797 at 10, 1.039 at 18 and 1.255 at 25 C. 
These constants are in good agreement with the values determined by Bohr. 
The second step, in the general equation given above, or the hydration 
of the carbon dioxide may take place in two ways, viz. : 

CO a +H a O=H a CO, 
or CO a +OH-=HCO a - 

Wilke, ., Chem.-Ztg., 39, 309 (1915); Z. anorg. allgem. Chem., 119, 365-79 (1922). 
Morgan, O. M., and Maass, O., Can. J. Research, 5, 162-99 (1931). 



CHEMICAL PROPERTIES OF CARBON DIOXIDE 115 

It is probable that both of these reactions take place simultaneously but 
that one of them may predominate depending on the pH of the liquid 
medium in which they take place. 

In 1912 McBain 6 called attention to the interesting fact that when an 
alkaline solution, containing phenol phthalcin, was mixed with a large excess 
of water saturated with carbon dioxide, the solution was not decolorized 
immediately but required from 5 to 20 seconds, depending upon conditions, 
for the color to fade. This time lag must, of course, be due to the hydra- 
tion reactions or the ion formation which depends upon them. Ways and 
means were then sought for determining the rate of this hydration and the 
amount of carbonic acid existing in solution under equilibrium conditions. 
A number of capable investigators 7 worked on the problem and from the 
conclusions arrived at from their labors, it is now generally conceded that 
solutions of carbon dioxide contain very small amounts of the rather 
strong metacarbonic acid. If a base is added to such a solution only a frac- 
tion, equivalent to the amount of H 2 CO 3 present, is neutralized at once ; the 
rest of the carbon dioxide enters into combination by the time-reaction 
having the velocity of the reaction CO 2 4- OH" = HCO 3 ". Attempts have 
been made to slow up the hydration reaction long enough to determine the 
amount of HoCOg present in the solution at any one time. Strohecker 
found that phenol, pyrocatechol, resorcinol and hydroquinone retarded it a 
sufficient time for one to measure the acidity of the solution. The result 
of an investigation in which resorcinol was used as the retarding agent 
showed that in a 0.038 per cent solution of carbon dioxide at 4 C. only 
0.56 per cent of the total carbon dioxide in the solution was in the form of 
H 2 CO 3 and that this small fraction only was ionized. 

Eucken and Griitzner 8 recently studied, by conductivity measurements, 
the velocity of hydration of carbon dioxide. According to these investi- 
gators, the time-reaction observed when an aqueous solution of carbon 
dioxide is neutralized, is due to an instantaneous conversion of the alkali 
to carbonate, which is then slowly converted to bicarbonate, by the excess 
carbon dioxide. They also calculated that at equilibrium 0.2 per cent of 
the total carbon dioxide in the solution is in the form of carbonic acid. 

Faurholt attempted to determine the rate of hydration and dehydration 
of carbon dioxide and while the probable error of his experiments was 
large (about 50 per cent) his conclusions and method of calculation are 
worth considering here. The rate of change in concentration of carbon 
dioxide in the reaction CO2 + HyO > H^COs is 



d [CO a ] 

- -=-MC0 2 ] ............. (37) 

at 

McBain, J. W., /. Chcm. Soc., 101, 814 (1912) 

T Thicl, A., Bcr., 46, 241, 867 (1913); Z. Elcktrochcm., 22, 423 (1916); Z. alltiem. Chcm., 121. 
211 (1922). Strohecker, E. R., Z. Nahr. Gcnussm., 31, 121-60 (1916). Thiel. A., and Strohecker, E. R., 
Bet., 47, 94S, 1061 (1914). Pusch, L.. Z. Elcktrochcm.. 22, 206, 293 (1916). Faurholt, C., Z. anorg. 
allacm. Chcm., 120, 85 (1922); /. chim. phys., 21, 400-55 (1924). 

8 Eucken, A., and Griitzner, II. G., Z. physik. Chcm., 125, 363-93 (1927). 



116 CARBON DIOXIDE 

and for the reaction CO 2 +OH-->HCO 8 - is 

-] [CO,] ............. (38) 



dt 

He found the numerical values of *i to be 0.0013 at C. and 0.0011 at 
18 C. while A' 2 equals 10 42 - 61 at and 10 43 - 24 at 18 C. As both reac- 
tions take place simultaneously the hydration can be represented by the 
equation d [COa ] 

1 = -(*+*. [OH-]) [C0 a ] ......... (39) 

dt 

in which the brackets indicate concentration. In solutions where the OH" 
concentration is constant it is evident that hydration of the carbon dioxide 
is a monomolccular reaction. When the pH of the liquid medium in which 
the hydration takes place is less than 8 then the OH" concentration is so 
small the reaction is practically COa + HuO-^IIoCOs but when the pH of 
the solution becomes greater than 10 it is the reaction CO 2 -hOH-- HCO 3 " 
that predominates. Between these two pH values of course both reactions 
are important. 

The dehydration reaction, according to Faurholt, may take place by 
the reversal of the two equations given above thus : 

H a CO,-H a O+C0 2 and HCO,--CO a +OH-. 
The rate of change of the first reaction is 

d [H 2 CO S ] 



(40) 



dt 
and of the second 

d [HCO a -] 

- - - =-MHC0 8 "] ........... (41) 

dt 

and the values for 6 3 are given as =*=!. at 0, 7.1 at 18 and for k 4 , 10* 5 - 50 
at and 10~ 4 - 52 at 18 C 

As in the case of hydration, between pH 8 and pH 10 the velocities of 
both dehydration reactions are quite similar. Below pll 8 the reaction 
becomes H 2 COa" > H 2 O + CO 2 while in more alkaline solutions than pH 10 
the bicarbonate decomposition prevails. 

The Dissociation Constant of Carbonic Acid. The principal dissocia- 
tion reaction of carbonic acid is that of a monobasic acid, producing thereby 
hydrogen ions and bicarbonate ions. Equilibrium calculations involving 
the production of these ions may, of course, be based on the actual amount 
of carbonic acid present or on the apparent amount estimated from the 
total carbon dioxide dissolved in the solution. It is therefore evident that 
there may be two sets of data on the dissociation constants of this acid 
depending on the method of calculation used. The apparent dissociation 
constant may be calculated from the relationship 

[H + ] [HC0 3 -] 
Ka= -- -- ............ (42) 

[H a CO,] + [CO a ] 



CHEMICAL PROPERTIES OF CARBON DIOXIDE 



117 



and the real dissociation constant from 



Kr= 



[H*] [HCOr] 



. . ........... (43) 

[H 2 CO S ] 

The experimental difficulty of determining the actual concentration of 
H 2 CO 3 in solution makes the values of K r somewhat less accurate than 
the values of K a . Strohecker 9 found 4.4 X 1O 4 for the value of K r at 4 C. 
and he points out the fact that carbonic acid is more strongly dissociated 
than formic acid (A' = 2.14x 10~ 4 ) of which it may he considered the 
hydroxy derivative. Haehnel 10 obtained a value of 4.4 X KH for K r at 15 
C. and his calculations indicated that 91 per cent of the carbonic acid 
present in the solution is dissociated into ions. Buytendykc, Brinkman and 
Mook 11 made twelve experiments in the temperature range from 14 to 
18 C. and always found values of K r between l.Sx 10' 4 and 4.0 X 10' 4 . 

The dissociation of H 2 CO :i under high pressures has been investigated 
by Muller and Luber. 12 They calculated that the concentration of true 
HoCOa at room temperature and SO atmospheres pressure is 6.36 xlO" 3 
mole (=0.386 gram) per liter. By the use of graded indicators the H+ 
concentration was found to be 125XIQ-* or pll = 2.9. From this value 
the degree of dissociation was calculated to be 0.196 per cent. The primary 
dissociation constant 13 of I^CO.i under SO atmospheres pressure of carbon 



TABLE 55. Experimental and Theoretical Data for the System Carbon Dioxide-Water. 
(Data from Morgan and Maass) 



CO 2 [CO 2 1 Partial Press. 

% moles/liter CO 2 mm. of Hg 



pH 



KaXlO" 



AtO C. 




0.0202 


0.00458 


0.0661 


0.01503 


0.1412 


0.03208 


0.2143 


0.04870 


0.2929 


0.06656 


0.3676 


0.08354 


At 10 C. 




0.0240 


0.00545 


0.0611 


0.01389 


0.1297 


0.02947 


0.1975 


0.04488 


0.2475 


0.05624 


At 18 C. 




0.0216 


0.00491 


0.0580 


0.01318 


0.1140 


0.02590 


0.1740 


0.03954 


At25C. 




0.0200 


0.00454 


0.0502 


0.01141 


0.1025 


0.02329 


0.1559 


0.03542 



57.0 
160.0 
352.7 
530.2 
681.3 
853.0 

81.7 
206.1 
424.1 
644.8 
835.6 

92.3 
229.8 
491.4 
744.5 

98.9 
253.2 
540.0 
822.2 

Strohecker, E. R., Z. Nahr.-Gcnussm.. 31, 121-60 (1916). 

10 Haehnel, O., Centr. Mineral Geol., 1920, 25-32. 

u Buytendyke, F. J. J., Brinkman, R., and Mook, H. W., Biochcm. /., 21, 576-84 (1927). 

"Muller, E., and Luber, A., Z. atwrg. allgem. Chcm. t 187, 209-30 (1930). 

M Muller, E. f and Luber, A., Z. anorg. allgem. Chem., 190, 427 (1930). 



0.000028 


4.55 


17.44 


0.000055 


4.26 


20.18 


0.000082 


4.09 


20.93 


0.000101 


4.00 


21.23 


0.000119 


3.92 


21.65 


0.000135 


3.87 


21.85 


0.000038 


4.42 


26.87 


0.000062 


4.21 


28.30 


0.000092 


4.04 


29.22 


0.000115 


3.94 


29.39 


0.000128 


3.89 


29.27 


0.000039 


4.41 


32.48 


0.000066 


4.18 


33.35 


0.000094 


4.03 


34.23 


0.000116 


3.94 


34.44 


0.000040 


4.40 


35.22 


0.000064 


4.19 


36.46 


0.000093 


4.03 


37.84 


0.000116 


3.94 


38.04 



118 

dioxide was found to be 



CARBON DIOXIDE 



[H*] [HCQr] 
[H,CO,] 



=3.06 XlO- 4 



The apparent dissociation constant has been more frequently and per- 
haps more accurately determined. Of the recorded data 14 it may suffice to 
mention here those obtained by Kendall and also those of Morgan and 
Maass. Kendall made conductivity measurements on water solutions of 
carbon dioxide under a partial pressure of carbon dioxide as it is found in 
ordinary atmospheric air. His results were: /C a = 2.24xlO r7 at 0, 
3.12 X 10- 7 at 18 and 3.50X 1Q- 7 at 25 C. The results obtained by Morgan 
and Maass are, without doubt, the most valuable of any yet obtained and 
these have been tabulated in Table 55. The variation of K a at various con- 
centrations of carbon dioxide is well illustrated by the isotherms in Figure 




fccg x 10* 



FIGURE 25. Relation of K to Concentration in the 
System CO a -H 2 O. (Data from Morgan and Maass.) 

25. Maclnnes and Belcher, 15 using a method involving galvanic cells and 
glass electrodes, obtained a value of 4.54 XlO~ 7 for the first dissociation 
constant at 25 C. 16 In a very recent work, however, measurements made 
by Kauko and Carlberg 17 support the older values of 3.50 X 10' 7 at 25 C. 
and 3.12 XlO- 7 at 18 C. 

The second stage of ionization is relatively of small importance due to 
the slight extent to which it takes place. In many calculations it may be 
left out of consideration altogether without seriously affecting the accuracy 
of the results. This stage of dissociation may be represented by the equa- 
tion HCO 3 ~ H + -f-CO 3 ~- and therefore the dissociation constant K2 

= [H + ] [CO 2 ~]/[HCO 3 -]. The value of K 2 was calculated by Bod- 

"Pfeiffer, E., Ann. phys., 23, 62S-6SO (1884). Knox, Ann. phys., 55, 44 (1895). Walker, J. and 
Cormak, W., /. Ckem. Soc., 77, 5-21 (1900). Kendall, J., /. Am. Chem. Soc., 38, 1480-97 (1916). 
Morgan. O. M., and Maass, O., Can. J. Research, 5, 162-99 (1931). 

"Maclnnes, D. A., and Belcher, D. t /. Am. Chem. Soc., 55, 2630-46 (1933). 

16 See also Carlberg, J., Acta Chem. Fcnnica, 8 B, 4 (1935). 

"Kauko, Y., and Carlberg, J., Z. physik. Chem., A 173, 141-9 (1935). 



CHEMICAL PROPERTIES OF CARBON DIOXIDE 119 

lander 18 and found to be 1.259X KH 1 . Prideau 10 obtained 6.0X 1CH 1 while 
somewhat later Menzel 20 found it to be 6.2 X KH 1 at 18 C. Maclnnes and 
Belcher in some recent measurements found the constant to be 5.61 X 10" 11 
at 25 C. 21 

The carbon dioxide equilibrium in sea water, is a subject of consider- 
able interest to those studying sea life and a number of investigations have 
been made on this subject. An interesting study was made by Kandler 22 
of the relations between hydrogen-ion concentration, free carbon dioxide 
and the alkalinity of sea water. This relationship was expressed in the 
following form: 



[Alky.] 

where KI is the first dissociation constant of H 2 CO 3 . The first and second 
apparent dissociation constants of carbonic acid in sea water at different 
salt contents have been determined by Buch 23 and his co-workers. 

The first dissociation constant of carbonic acid in hemoglobin solutions 
has been measured by Margaria and Green. 24 

*' The pH of Water Solutions of Carbon Dioxide. While the dissocia- 
tion data of carbonic acid is of great fundamental importance, from a 
practical point of view the true acidity expressed in terms of pH units is 
more useful. Byke 25 has calculated the pH values for solutions of carbon 
dioxide in pure water. The range covered in his calculations extends from 
a partial pressure of carbon dioxide of one atmosphere to zero. The equa- 
tions for carbonic acid equilibria and the values of the constants used are 
as follows: 

(1) [H + ] [OH-]=K=0.54X10- 14 (20 C.) 

(2) [H + ] [HC0 3 -]/H 2 C0 3 =Av=3.18xlO- T (20 C.) 

(3) [H + ] [CO 3 -]/rHC0 3 -] = fr 2 =3.54xlO- u (2ft C.) 

(4) [H 2 CO 3 ]=rP c=3.093 (20 C.) 

(5) [H+]=2 



The value of the hydrogen-ion concentration can therefore be calculated 
from the equation 

2 ki k 3 ncP ki ncP k w 

(6) [H + ]= - +- - + 

[H + ]' [H + ] [H+] 

by substituting various values for P, the partial pressure of carbon dioxide 
with which the pure water is in equilibrium. The results of Byck's calcu- 

"Bodlander, G., Z. physik. Chcm., 35, 23 (1900). 

"Prideau, E. B. R., Proc. Roy. Soc. (London), 91, A 535 (1915). 

Menzel, H. f Z. physik. Chcm., 100, 276 (1922). 

Sec also Kauko. Y. f Acta. Chcm. Pennies 5B, 53 (1932). 

Kandler, R., Intern. Rev. aes. Hydrobiol. Hydroff., 24, 177 (1930). 

Mfiuch, K., Finskat Kemistsamfundcts Medd. t 40, 55-62 (1931). Buch. K., Wattenberj?, H., and 
Harvey, H. W., Nature, 128. 4011-2 (1931). Buch, K., Harvey, H. W., and Wattenberg, H., 
Natuntrissenschaften, 19, 773 (1931). 

"Margaria, R., and Green. A. A., J. Biol. Chcm., 102, 611-34 (1933). 

Byke, H. T. f Science, 75, 224 (1932). 



120 



CARBON DIOXIDE 



lations are given graphically in Figure 26. It should be kept in mind that 
such a calculation carries with it a certain error. Morgan and Maass have 
already shown that the dissociation constant depends upon the carbon 
dioxide concentration and is not constant as is assumed in these calcula- 
tions. 










































^ 
























- 








\ 


\ 




















- 










\ 


\ 


















- 












/ 


\ 














pH 









^ 


f 


f 






\ 












J 




*5 
& 


/ 














\ 
































\ 






























\ 


\ 






3 


-II 


t -9 




-; 


-6 






-: 


-; 




c 


> , 


4 





Log of Partial Pressure of CG In At mod. at 2(fC. 

FIGURE 26. pH Values of Carbonic Acid Solu- 
tions at Different Pressures of Carbon Dioxide. 



Values for pH of solutions of carbon dioxide in water at pressures 
above 1 atmos. have been determined colorimetrically by Moore and 
Buchanan. 20 These measurements given in Table 56 were made in an 
attempt to explain the action of carbon dioxide in carbonated beverages 
in inhibiting the growth of bacteria. The maximum acidity was reached 
with a pH of 3.3 at a pressure of 9.5 atmos., the conclusion was therefore 

"Moore, M. B., with Buchanan, J. H., Iowa State College, /. Sci. t 4, 431-40 (1930). 



CHEMICAL PROPERTIES OF CARBON DIOXIDE 121 

reached that the action of carbon dioxide solutions on bacteria was due, in 
part at least, to some factor other than the increase of H ion concentra- 
tion of the solution. 

TABLE S6.pII of Carbon Dioxide Solutions. 
(Colorimetric measurements by Moore and Buchanan) 

r-Temperature 25 -^ /^-Temperature > 

CO 2 pressure x T CO 2 pressure ^u 

Atmos. pH Atmos. pH 

1.0 3.7 1.0 3.5 

1.7 3.5 1.4 3.4 

2.5 3.4 2.6 3.3 

2.9 3.4 3.6 3.3 

3.7 3.4 8.3 3.3 

3.8 3.4 15.3 3.2 

5.4 3.3 23.4 3.2 
5.8 3.3 

7.2 3.3 

7.8 3.3 

9.5 3.3 
10.5 3.3 
12.7 3.3 
18.7 3.3 
33.3 3.3 

Action of Carbonic Acid on Calcium Compounds. Since the time of 
Cavendish (1766) it has been known that carbon dioxide precipitates cal- 
cium carbonate from a solution of calcium hydroxide and that continued 
addition of the gas redissolvcs this precipitate. Furthermore Irvine 27 found 
that heat was given off during the first stage of this reaction and another 
heat evolution was obtained when the precipitate started to dissolve. The 
usually accepted explanation of this reaction is that the calcium carbonate, 
CaCO 3 , formed during the precipitation process combines with the excess 
carbonic acid to produce the soluble calcium bicarbonate CaH 2 (CO 3 )2. 
This simple explanation, of course, docs not take into consideration ionic 
reactions taking place between CO 3 ", HCO 3 ~, H + , OH" and the molecules 
of H 2 O, CaCO 3 and H 2 CO 3 which produce them. The net result of all 
reactions is that the degree of solubility of calcium carbonate is a function 
of the carbon dioxide concentration and of course this concentration 
depends upon the partial pressure of carbon dioxide above the solution. 
Thus it can be shown that even a slight change in the partial pressure of 
carbon dioxide in normal air may bring about the solution or deposition of 
large quantities of calcium carbonate in natural surface waters. 

Cameron and Robinson 28 questioned this explanation of the solubility 
of calcium carbonate in solutions of carbon dioxide and stated that it could 
be regarded just as logically and more conveniently as due to the specific 
solvent action of the carbon dioxide water mixtures. This idea has 
received practically no support from recent investigators and the belief 
in the bicarbonate formation is now stronger than ever. As a matter of 

"Irvine, R., Chem. News, 63, 192 (1891). 

"Cameron, F. K., and Robinson, W. O., J. Phys. Client., 12, 561-73 (1908). 



122 CARBON DIOXIDE 

fact it is believed that the isolation of calcium bicarbonate in the solid con- 
dition is entirely feasible as in the case of magnesium bicarbonate which 
was found by Haehnel 29 to be sufficiently stable to be detected in the solid 
state at -5 C. 

From a practical point of view the solubility reactions involved in the 
system CaCO 3 H 2 O CO 2 have many applications. Some of the most 
important of these are, scale formation in steam boilers and in water pipes, 
bone calcification and blood equilibria in physiological processes as well as 
rock formation and solution under geological conditions. 

The Solubility of Calcium Carbonate in Water Solutions of Carbon 
Dioxide. The reactions involved in the process of solution of calcium 
carbonate in water solutions of carbon dioxide are not simple as was indi- 
cated in this introductory statement. Johnston and Williamson 30 give a 
very clear and detailed explanation of the various ionic reactions taking 
place when metallic hydroxides of certain types are treated with solutions 
of carbon dioxide and the solubility curve of calcite in aqueous solutions of 
carbon dioxide which they used in this discussion is reproduced here as 
Figure 27. 

When carbon dioxide gas is passed into a solution of Ca(OH) 2 the pre- 
dominating hydration reaction is CO 2 + OH- = HCO 3 ~. The [OH~] being 
thus decreased causes the formation of more Ca ++ in order to keep the solu- 
bility product [Ca + +] fOH"l 2 constant. The reactions taking place are : 

Ca(OH) 2 =Ca ++ +2OH- 

C0 2 +OH-=HC(V 
or combined Ca(OH) 3 +CO a =Ca + *+OH-+HCO a -. 

Now if one measures the solubility of Ca(OH) 2 under increasing partial 
pressures of carbon dioxide by a determination of its calcium ion the solu- 
bility of the base apparently increases, whereas if the hydroxyl ion is deter- 
mined the solubility of the base seems to decrease. The solution, however, 
now contains in addition molecules of Ca(HCO 3 ) 2 produced by the equili- 
brium set up between the calcium and the bicarbonate ions. Furthermore 
the bicarbonate ion also dissociates slightly to produce H+ and CO 3 ~~ and 
when the product of fCa+ + ] [CO 3 ~] reaches the proper value then CaCO 3 
is precipitated. This final reaction results in a decrease of the Ca ++ which 
starts at point PI (Fig. 27) and continues with the addition of carbon 
dioxide until the minimum value is reached at PQ. Meanwhile the OH" 
has decreased until a point is reached (Po) where the predominating hydra- 
tion reaction is CO 2 + H 2 O = H 2 CO 3 = H + + HCO 3 - (according to Faurholt 
this reaction predominates below pH 8) and the formation of bicarbonate 
ion becomes the important reaction. The [CO 3 ~~] then decreases and the 
f Ca ++ ] increases until at the concentration represented by point P 2 the pre- 
cipitation value of the product [Ca* + ] [HCO 3 "1 2 is reached, which is a 
transition pressure at which both carbonate and bicarbonate are present as 

"Haehnel, O., /. prakt. Chem. (2), 108, 61-74 (1924). 

w Johnston, J., and Williamson, E. D.. J. Am. Chem. Soc., 38, 975-83 (1916). 



CHEMICAL PROPERTIES OF CARBON DIOXIDE 



123 



stable solid phases. Beyond F the bicarbonate alone is stable, and its total 
solubility falls off very slowly with further increase in the partial pressure 
of carbon dioxide. 



! 






-13 -S -5 -I *l 

Log. P in Afmo4phrJ 

FIGURE 27. System CaO H 2 O CO 2 at 16 C. The stable 
solid phase to the left of P l is hydroxide, between Pi and P a is 
carbonate and to the right of P 2 bicarbonate. The curve repre- 
sents the solubility as determined by estimation of calcium. The 
dotted lines by the determination of solubility from the various 
ions. (From Johnson and Williamson.) 

The data on which Figure 27 was based were calculated by Johnston 
and Williamson and the results of these calculations are given in Table 57. 
For the methods of calculation and the values of the constants used one is 
referred to the original paper. 

Recently determinations of the solubility of calcite in water solutions 
of carbon dioxide have been made by W. D. Kline 31 at partial pressures of 



TABLE 57.- 
16 C. 



-Calculated Ion-Concentrations and Solubility of Calcite in 
in Contact with Air Containing the Partial Pressure P of 
(By Johnston and Williamson) 

P atmos. [HCO,-] X 10 4 [OH-] X 10* f CO 8 -] X 10 4 [Ca ++ ] X 10 4 



2.15 XlO- 4 
7.63 XlO- 8 
7.62 XlO- 6 
6.07x10-' 
3.85 XlO- 7 
3.73 XlO- 7 
2.19 XlO- 7 
6.14X10- 8 
9.78X10-' 
2.80 XlO- 10 

3.16 XlO- 14 



10.0 
7.0 
3.0 
1.0 
0.80 
0.787 
0.60 
0.30 
0.10 
0.01 
0.0000235 



0.0147 
0.034 
0.147 
0.614 
0.774 
0.787 
1.02 
1.82 
3.82 
13.3 
277.0 



0.188 
0.260 
0.478 
0.666 
0.672 
0.672 
0.665 
0.593 
0.414 
0.144 
0.0071 



5.197 
3.777 
2.051 
1.473 
1.459 
1.459 
1.476 
1.654 
2.377 
6.81 
138.5 



Water at 
CO,. 

Parts 
CaCO 3 per 
million 
56 
40 
22 
16.0 
15.9 
15.9 
16.0 
18 
26 
74 
2000 



Sec Frear, G. L., and Johnston, J., /. Am. Chem. Soc. t 51, 2086 (1929). 



124 CARBON DIOXIDE 

carbon dioxide from about 1 atmos. down to 0.00031 atmos. These data 
seem to be more reliable than any hitherto available and they are repro- 
duced here as Table 58. 

TABLE 58. Solubility of Calcitc in Water Solutions of Carbon Dioxide at 25 C. 

(Data by W. D. Kline) 

Partial pressure Ca+* HCCV 

of CO 2 Millimoles per Millimoles per 

atmos. kilo H 2 O kilo H 2 O 

0.00031 0.52 1.02 

.00038 0.56 1.10 

.00093 0.76 1.50 

.00334 1.17 2.32 

.00690 1.51 3.01 

.0160 2.01 4.01 

.0432 2.87 5.74 

.1116 4.03 8.06 

.9684 8.91 17.82 

A plot of the most reliable solubility data including those of Kline was 
made by Frear and Johnston for the system CaCO H 2 O CO2 at a tem- 
perature of 25 C. Values read from this curve are as follows : 

CO, partial pressure atmos 0.00032 0.001 0.01 0.1 1.0 10 

CaCO,, millimoles per kilo H a O.... 0.53 0.78 1.7 3.9 9.0 22.5 

The temperature coefficient of solubility of calcite in carbonic acid solu- 
tions has also been determined by these investigators. They find that within 
the accuracy of the measurements, this coefficient is independent of the 
partial pressure of carbon dioxide especially below one atmosphere. There- 
fore it is sufficient to give the ratio r of the solubility at t to that at 25 
These ratios for various temperatures are : 



10 20 25 30 50 

1.8 1.4 1.1 1.0 0.9 0.6 



Carbon Dioxide in Natural Waters. Carbon dioxide in natural waters 
such as well water, surface waters and the ocean plays an important role 
in determining the extent of temporary hardness. Johnston 32 gives an 
excellent discussion of the chemistry involved and discusses practical 
methods of making determinations. A detailed discussion of the subject 
here, perhaps, would lead too far afield. It might be mentioned, however, 
that one of the uses of carbon dioxide is the treatment of city water supplies 
for the control of hardness and this use seems to be growing in 
importance. 33 

The change in the pH of natural waters with change of carbon dioxide 
and calcium carbonate concentration has been calculated by Newell 34 with 

" Johnston, J., /. Am. Chem. Soc., 38, 947-75 (1916). 

"Kelly, E. M. f /. Am. Water Works Assoc., 24, 1165-72 (1932). 

* Newell, I. L., /. Am. Water Works Assoc., 24, 560-1 (1932). 



CHEMICAL PROPERTIES OF CARBON DIOXIDE 125 

the aid of an equation proposed by Tillman. This equation may be put 
into the following form : 

Alkalinity (as CaCO,) X 0.203 XlO T 

pH=log (44) 



90- 


pH 


- 


CO, 




_ 




-100 


as- 




r-90 






-80 


- 




L 70 


- 




-60 


8.0- 


Alkalinity 


r-50 


. 




1000 


--4-0 


7.5- 




boo 


r 30 


- 




^300 


L 


~ 




-200 


:_ 20 







100 




7.0- 











g 


b|g | 




&5 - 


f 


-20 S 


-10 




u 


i. 


- 9 





& 


10 - 


8 


- 


w 


: 5 


7 




I 


_ V. 

~l ifi 


6 


6.0- 




3 


-5 






- 2 










4 






1 










- 3 


55- 










2 


5.0- 










-1 


45- 







FIGURE 28. Alignment Chart for pH, Alkalinity and CO 2 . Based upon 
Tillman's Formula 

Alkalinity X 0.203 XlO T 

pH=log 

Free CO a 

when Alkalinity (as CaCO 2 ) and CO a are in parts per Million. 
(Chart Constructed by Newell) 



126 CARBON DIOXIDE 

where alkalinity and carbon dioxide are expressed in parts per million. 
Figure 28 shows a nomogram constructed by Newell giving the relation 
between these variables which has considerable value for quickly making 
such calculations. 

Action of Carbon Dioxide on Calcium Cyanamide. Franck and 
Meppen 35 while attempting to find a method of removing the free carbon 
from commercial calcium cyanamicle made a careful study of the system 
CaCN 2 -C-CO 2 . They found that between the temperatures 600 and 
1000 C. two reactions were possible; first 2 CaCN 2 + CO 2 = 2CaO + 3C 
+2N 2 and second CO 2 +C = 2CO. Also above 1000 C. a third reaction 
takes place in which the CO from the second reaction combines with the 
calcium cyanamide producing CaO, N and C. The second reaction is the 
fastest, yet it was found to be impossible to separate the carbon from the 
cyanamide because the first reaction takes place to a considerable extent 
before the end of the reaction between carbon and carbon dioxide. 

Action of Carbon Dioxide on Sulfides of Sodium and Calcium. A 

method has been developed in which carbon dioxide is used for treating 
alkali waste for the recovery of sulfur or sulfur compounds. This process 
was at one time of some commercial importance in connection with plants 
using the LeBlanc process for making soda ash. According to Berl and 
Rittener 30 the carbon dioxide is used for freeing the raw soda liquors from 
sulfides, silicates and aluminates as well as from what iron may be present. 
The reaction on the sodium sulfide in the solution is NaoS-f CO 2 4-H 2 O 
?NaSH + NaHCO., and NaSH-f CO 2 + H 2 O?NaHCO 3 H-H 2 S. These 
authors show that all the hydrogen sulfide is not expelled from the solution 
until the Na 2 CO 3 present has been completely converted into NaHCO^. On 
treating the calcium sulfide with carbon dioxide the reaction follows some- 
what the same course, the final reaction being Ca(SH) 2 + CO 2 + H 2 O = 
CaCOa-f H 2 S. The gas escaping from the reaction tank has an H 2 S concen- 
tration from 44 per cent to 71 per cent. The carbon dioxide used in this 
reaction is usually obtained from kiln gas. 

Action of Carbonic Acid on Calcium Phosphate. Carbonic acid reacts 
to a certain extent with secondary and tertiary calcium phosphates with 
the production of primary calcium phosphate. The equation for the reaction 
between carbonic acid and secondary calcium phosphate may be written 
2CaHPO 4 + H 2 CO; { = Ca(HoPO 4 ) 2 + CaCO 3 . The calcium carbonate also 
reacts with carbonic acid to produce calcium bicarbonate. This reaction 
has recently been studied by Miiller and Knofel 37 who found that 
Ca 3 (PO 4 ) 2 dissolves to the extent of 0.754 grams of P 2 O r> per liter of solu- 
tion saturated with CO 2 at 60 atmospheres pressure. Under the same con- 
ditions bone ash dissolves to the extent of 0.589 grams PoO 5 at and 
0.333 grams P 2 O.-, at 20 C. Phosphorite is much less soluble giving only 

88 Franck, H. H., and Meppen, B., Z. an<jew. Chem., 43, 726-32 (1930). 
86 Berl, E., and Rittener. A., Z. antjrw. Chcm., 20, 1637-42 (1907). 
w Mullcr, E. f and Knofel, J., Z. anorg. allgem. Chcm., 194, 258-60 (1930). 



CHEMICAL PROPERTIES OF CARBON DIOXIDE 127 

TABLE 59. Solubility of Secondary Calcium Phosphate in Solutions of Carbon 

Dioxide Saturated Under a Pressure of 60 Atmospheres. 

(Data by Miiller and Knofel) 

Temp. P a O. CaO Temp. P a O. CaO 

C. gm. per liter gm. per liter C. gm. per liter gm. per liter 

1.386 1.117 100 0.458 0.266 

20 1.037 0.840 120 0.490 0.242 

40 0.937 0.800 140 0.488 0.214 

60 0.743 0.632 160 0.484 0.240 

80 0.444 0.374 

0.035 grams of P 2 O r , per liter at C. The effect of temperature changes 
on the solubility of secondary calcium phosphate is shown in Table 59. 

Action of Carbon Dioxide Solutions on Alkaline Earth Silicates. The 

action of carbonic acid on alkaline earth silicates may be illustrated by 
the calcium silicate reaction simply expressed as CaSiO 3 +2H 2 CO3 = Ca 
(HCO 3 )2+H 2 SiO 3 . It is at once apparent that this reaction has a consid- 
erable bearing on rock and soil disintegration. Several studies having to do 
with this phase of rock action have been made but perhaps the most interest- 
ing is the recent work published by Miiller and Lubberger. 38 The change in 
solubility of the alkaline earth silicates with change in temperature as 
determined by these authors is indicated in Table 60 while the change in 
solubility with change in pressure of carbon dioxide is given in Table 61. 

TABLE 60. Solubility of Alkaline Earth Silicates in Solutions of Carbon Dioxide 

Under 50 Atmospheres Pressure. 

(Data by Miiller and Lubberger) 

Reaction time J hours. 

Temp. C. 



20 

40 

60 

80 
100 
120 
140 

TABLE 61. Solubility of Alkaline Earth Bicarbonates and Silicates in 
Water Solutions of Carbon Dioxide Under Varying Pressures at 20 C. 

Concentrations expressed as grams of salt per liter of solution. 

(Data by Miiller and Lubberger) 
Pressure 

of CO, Ca(HCO,) a CaSiOa Sr(HCO 8 ) 3 SrSiO 3 Ba(HCO,), BaSiO, 
Atmos. 

50 
40 
30 
20 
10 


Miiller, E., and Lubberger, W., Z. anorg. allgem. Chem., 194, 161-7 (1930). 



CaSiOa 


SrSiOa 


BaSiO, 


gm. per liter 


gm. per liter 


gm. per liter 


3.712 


4.123 


6.001 


3.503 


3.799 


5.751 


3.309 


3.563 


5.401 


2.900 


3.111 


4.853 


2.104 


2,323 


4.179 


0.907 


1.012 


2.582 


0.950 


1.040 


2.594 


0.956 


1.050 


2.590 



4.875 
4.875 
4.871 
4.325 
2.993 
1.387 


3.503 
3.501 
3.498 
3.106 
2.149 
0.996 


4.858 
4.859 
4.856 
4.266 
3.088 
1.349 


3.799 
3.800 
3.797 
3.336 
2.416 
1.055 


6.981 
6.975 
6.975 
6.453 
6.376 
3.218 


5.751 
5.746 
5.746 
5.316 
5.253 
2.651 



128 



CARBON DIOXIDE 



Action of Carbonic Acid on Magnesium Compounds. The existing 
data on the action of carbon dioxide solutions on magnesium compounds 
is not as extensive as those on the action of carbon dioxide on calcium 
compounds. The reactions, however, are quite similar and the way com- 
pounds of calcium and magnesium are associated in nature makes a study 
of both systems of considerable importance. It will serve our purpose 
here to consider only a few of the most modern researches on the solubility 
of magnesium carbonate in aqueous solutions of carbon dioxide. The 
importance of the work done previously to this should not be depreciated, 
however, as most of the information we now have on the subject has been 
contributed by such men as Raikow, 39 Davis, 40 Cameron and Robinson 41 
and especially Johnston 44 as well many other investigators. 

Solubility of Magnesium Carbonate in Solutions of Carbon Dioxide. 

Haehnel 43 reports some interesting results from solubility measurements 
on magnesium carbonate. He found that at 18 C. the solubility of magne- 
sium carbonate in water saturated with carbon dioxide increased with 
increasing carbon dioxide pressures up to 18 atmos. and that no further 

TABLE 62. Molal Concentration (Expressed as Millimols per Kilo, of Water) of Ions 
in Equilibrium with a Series of CO t Pressures in the System 

MgCO 8 3H 2 0-H 2 0-C0 2 at 25 C. 



(Data by Kline) 



Pressure 
Atmos. 

0.000107 
.000113 
.000170 
.000179 
.000197 
.000210 
.000233 
.000251 
.000310 
.000376 
.000380 

.000510 

.000680 

.000845 

.000887 

.000930 

.00160 

.00334 

.00690 

.0150 

.0432 

.1116 

.9684 



xlO 3 

4.33 

4.45 

5.77 

5.93 

6.58 

7.08 

7.80 

8.07 

10.13 

12.96 

13.55 

14.37 
15.12 
15.66 
15.93 
16.24 
18.59 
22.10 
25.07 
31.27 
46.01 
62.66 
213.5 



[HC0 3 -] 


[CO,-] 


XlO 8 


X10 S 


4.88 


1.89 


5.01 


1.95 


7.45 


2.05 


7.63 


2.12 


7.95 


2.61 


8.06 


3.05 


8.37 


3.61 


8.55 


3.80 


11.84 


4.21 


14.04 


5.94 


14.32 


6.39 


17.10 


5.82 


18.72 


5.76 


19.90 


5.71 


20.46 


5.70 


21.19 


5.65 


26.98 


5.10 


35.48 


4.36 


44.68 


2.73 


60.22 


1.16 


89.98 


1.02 


123.6 


0.85 


426.9 


.... 



Ionic 
strength 

0.0149 
.0153 
.0194 
.0199 
.0224 
.0243 
.0270 
.0280 
.0346 
.0448 
.0470 

.0489 
.0511 
.0527 
.0535 
.0544 
.0609 
.0707 
.0779 
.0950 
.1390 
.1889 
.6405 



[OH-1 
XlO 5 

3.84 
3.73 
3.69 
3.59 
3.10 
3.23 
3.03 
2.87 
3.22 
3.14 



Solid 
phase 



Mg(OH), 



MgC0 3 -3H a O 



Raikow, P. N., Chem.-ZtR., 31, 55 (1907). 

Davis, W. A., J. Soc. Chcm. Ind. t 25, 788, 973 (1905). 

Cameron, F. K., and Robinson, W. O., /. Phys. Chem., 12, 561 (1908). 

Johnston, J. f J. Am. Chem. Soc., 37, 2001 (1915). 

Haehnel, O., /. Prakt. Chem. (2), 108, 61-74 (1924). 



CHEMICAL PROPERTIES OF CARBON DIOXIDE 129 

increase in solubility took place between this pressure and 56 atmos. At the 
point of maximum solubility the solution contained 7.49 grams of MgCOs 
or 13.00 grams of Mg(HCO 3 )2 in 100 grams of water. He also found that a 
solution of Mg(HCOa)2 prepared at high pressures of carbon dioxide is 
quite stable at ordinary temperatures but if heated to 65 C. a vigorous 
evolution of carbon dioxide takes place with a precipitation of crystals of 
MgCOs 3H2O. He also found that magnesium bicarbonate is sufficiently 
stable to be detected in the solid state at -5 C. 

The solubility measurements made by Kline 44 on magnesium carbonate 
(nesquehonite) in carbon dioxide solutions are not only confidence inspiring 
but cover a range of carbon dioxide pressures of considerable importance. 
His results include determined and calculated concentrations of the ions 
concerned and are given in Table 62 while Table 63 lists the concentration 

TABLE 63. Molality of Magncsittm in Saturated 

Solutions of the Carbonate at Various Pressures of 

Carbon Dioxide. 

Temp.=25 C. 
(Data by Kline) 

Pressure r*r , Pressure r\r~-i 

Atmos. [M * ] Atmos. [M * ] 

0.001 0.0178 07 0.181 

.01 .0270 1.0 .217 

.05 .0489 2.0 287 

.1 .0660 5.0 .384 

.3 .117 10.0 .471 

.5 .152 15.0 .526 

of magnesium in water solutions of carbon dioxide under pressures extend- 
ing as high as IS atmospheres. These latter data were interpolated from 
the curve of most probable solubility measurements. 

Solubility measurements of magnesium carbonate in aqueous solutions 
charged with carbonic acid gas were also made by Terada. 45 His work, 
however, was concerned principally with the velocity of the reactions. Thus 
the solution of MgO or Mg(OH) 2 in water solutions of carbon dioxide 
was found to be very rapid while MgCO 3 .3H 2 O dissolved very slowly. 
Studies of bicarbonate reactions of Ca and Mg have also been made recently 
by Stumper 40 but his measurements also dealt with reaction velocities 
especially where they were related to the industrial process of softening 
hard water. 

Action of Carbon Dioxide on Aqueous Lead Acetate Solutions. When 
gaseous carbon dioxide is passed through a solution of lead acetate, either 
normal or basic lead carbonate is precipitated. The nature and yield of 
precipitate depends upon several factors, the concentration of the acetate 
solution being one of the most important. Thus Altmann 47 on passing 

Kline, Walter, /. Am. Chcm. Soc., 51, 2093-7 (1929). 

48 Terada, Kiyomatsu, Bull. Inst. Phys. Chcm. Research (Tokyo), 7, 452-65 (1928). 

48 Stumper, R. f Z. anorg. allgem. C/irm., 202, '227-60 (1931). 

Altmann, A., Z. anorg. allgem. Chem. t 52, 219-28 (1907). 



130 



CARBON DIOXIDE 



carbon dioxide through a N/2 lead acetate solution at 20 C. obtained 32.8 
per cent of the lead precipitated and when the temperature was raised to 
100 C. only 6.32 per cent of the lead was precipitated. In a N/50 solution 
of lead acetate at 20 C., 80.21 per cent of the lead was precipitated and 
at 100 C., 48.25 per cent of the lead was precipitated. Solutions of higher 
concentrations gave precipitates of normal carbonate while hot dilute solu- 
tions gave basic lead carbonate (2PbCO 3 .Pb(OH) 2 ). Hot concentrated 
solutions of lead acetate gave various mixtures of the normal and basic 
carbonates. 

These conclusions were confirmed in general by Yamasaki 48 who found 
that diluting the lead acetate solution down to O.I N increased the precipi- 
tate of lead carbonate but that in less concentrated solutions the amount of 
precipitate was independent of the concentration. Concentrations of 0.1 N 
or below give a ratio of acetic acid to lead acetate as 4.3 is to 1. When 




o Time Hra. 

FIGURE 29. Conversion of Starch to Dextrose by Carbon 
Dioxide Solution at 1000 Ibs. per square inch. 

acetic acid was added to the lead acetate solution and carbon dioxide 
passed through, the proportion of acid to lead acetate was the same as in 
the case where no acid was added, if the total concentration of the acetate 
radical was lower than 0.1 N. In dilute solutions of lead acetate, the lead 
was almost completely precipitated by carbon dioxide when sodium acetate 
was added in quantity more than equivalent to the lead salt. 

Yamasaki, K., Mem. Coll. Sci. Eng., Kyoto Imp. Univ., 1, 177-83, 27576 (1907). 



CHEMICAL PROPERTIES OP CARBON DIOXIDE 131 

The Hydration Action of Carbonic Acid on Starch. Under high 
pressures (up to 2500 pounds per square inch) carbon dioxide solutions 
displace acetic acid from aqueous solutions of calcium acetate until the 
resulting acidity corresponds to a solution containing about 10 per cent by 
weight of acetic acid. 49 While it is true that this acid concentration is only 
moderate, it is conceivable that certain commercial reactions might be 
carried out in carbon dioxide solutions to an advantage. Dewey and Krase 50 
studied the effect of aqueous solutions of carbon dioxide, saturated at about 
1000 pounds per square inch, on starch and found that the hydrolysis of the 
starch to dextrose is a linear function of the time. It was also found that 
at 216 C. complete hydrolysis of the starch required 1.5 hours, while at 
180 C. 5 hours were necessary to complete the reaction. The results 
obtained by these investigators at three different temperatures are shown 
in Figure 29. 

REACTIONS WITH GASEOUS CARBON DIOXIDE 

The carbon dioxide molecule is relatively stable and under ordinary con- 
ditions does not break up readily into simpler compounds. It is possible, 
however, to decompose it to a certain extent at high temperatures. It has 
already been shown (see page 64) that the degree of dissociation is a func- 
tion of the temperature. The dissociating reaction under these conditions is 
2CO2*=*2CO + O 2 . Various other conditions will also bring about this 
decomposition reaction, as for instance, ultra-violet light which decomposes 
it to the extent of 3 per cent at atmospheric pressure and up to 46 per cent 
at 36 mm. pressure. 61 That the presence of moisture in the gas tends to 
greatly decrease the degree of dissociation has been shown by several inves- 
tigators. Sulfur dioxide and potassium cyanide likewise retard the decom- 
position reaction. Radium radiations tend to decompose carbon dioxide but 
the reaction is slow and proceeds only slightly towards the carbon monoxide 
and oxygen side of the equation. Electric sparks passed through carbon 
dioxide gas also decomposes it slightly. When the carbon monoxide and 
oxygen concentration reaches a certain value a recombination takes place 
which apparently stops the decomposition. A silent discharge also decom- 
poses carbon dioxide and the resulting oxygen is partially converted to 
ozone. The action of the ozone on the carbon monoxide reverses the reac- 
tion thus preventing any considerable dissociation. 

Reduction of Carbon Dioxide by Hydrogen. Perhaps the most usual 
reduction reaction produced by hydrogen on carbon dioxide is CO2+Ho 
^CO + H 2 O. However this is by no means the only reaction possible as 
various carlxMi compounds such as formaldehyde, methane, ethane and var- 
ious other reduction products may be formed under certain conditions and 
especially under the influence of certain catalytic agents. 

Goodman, J. B., and Krase, N. W., Chem. Met. Eng., 36, 162 (1929). 
80 Dewey, M. A., and Krase, N. W., Ind. End. Chem., 23, 1436-7 (1931). 
"Chadwick, S., Ramsbottom, J. ., and Chapman, D. L., /. Chem. Soc., 91, 942 (1906). 



132 CARBON DIOXIDE 

A few of the most modern researches dealing with this subject will be 
considered. Randall and Shiffler 52 suggest that the deposition of carbon 
from reacting mixtures of CO 2 and Hi may take place according to the 
equation CO 2 +2H 2 ^C+2H 2 O with all of the reactants in the gaseous 
form except carbon which is graphitic. Srikantan 53 studied the reaction 
under the influence of the catalytic action of platinum and platinum iridium 
alloy. His results were concerned more especially with reaction velocities 
at various temperatures and conditions of catalysts. Peters and Kuester 54 
found that a mixture of CO 2 and H 2 under the influence of an electric 
discharge at reduced pressure reacted according to the equation CO 2 + H 2 
-*H 2 O + CO-10.4 Cal. Bahr 53 studied the reaction at moderate temper- 
atures using various catalysts to promote the reaction. He found that with 
metallic Cu the reaction was noticeable at 200 C. With the employment of 
Cu.Cr 2 Os, Fe.Cu, Fe.Co and Co.CuZn as contact materials with tempera- 
tures between 200 and 450 C. the CO quantities obtained were as high 
as 16 per cent of the gas mixture. With a slow current of the gas mixture 
of CO 2 and H 2 over the catalysts the reduction of the CO 2 went to methane. 

Reduction of Carbon Dioxide with Carbon. The reduction of carbon 
dioxide with carbon at elevated temperatures is of considerable commer- 
cial importance. Its most important application is in the combustion of 
ordinary carbonaceous fuels during which carbon monoxide is practically 
always produced, to some extent, by the reduction of carbon dioxide. This 
topic will be treated under the subject of combustion (see page 148) and 
at this point perhaps a very brief reference to it will suffice. 

It so happens that a large number of reported data on tlie equilibrium 
relations of the gaseous components of the system CO 2 + C >2CO have 
been made at 800 C. This rather arbitrary temperature selection was made 
because of the fact that at this temperature the speed of the reaction is 
sufficiently great to permit of laboratory treatment and that the carbon 
dioxide concentration at this point is sufficiently high to make its determina- 
tion easy. Data at this temperature can be selected from a number of 
sources although it must be admitted that the agreement between them is 
not especially good. Dent and Cobb 50 however, point out that this lack 
of agreement is without doubt due to the various forms of carbon used by 
the different investigators. Thus one would hardly expect reactions of 
carbon dioxide with coke, charcoal and graphite to follow exactly the same 
course because of their different energy contents. Some of the results of 
various investigators in this field have been selected and the composition of 
the gaseous phase under equilibrium conditions at 800 C. are as follows : 

"Randall, Merle and Shiffler, W. H., Ind. Enq. Chem., 21, 941 (1929). 

M Srikantan, B. S., /. Indian Chem. Soc., 6, 931-47, 949-58, 959-67 (1929) . 

"Peters, K. and Kuester, H., Z. physik. Chem., Abt. A, 148, 284-303 (1930). 

88 Bahr, Herbert. Ges. Abhandl. Kenntnis Kohle, 8, 219-24; Chem. Zentr., 1930, I, 185-6. 

Dent, F. J., and Cobb, J. W., 7. Chem. Soc. t 1929, 1903-12. 



CHEMICAL PROPERTIES OF CARBON DIOXIDE 133 

CO,% CO% Observer Reference 

i9 25 o Boudouard, ^(nn. cAi'm* #Ay*., 24, 1 (1901). 

If} 2 Mayer and J acob y J - Gasbeleucht., 52, 282 (1909). 

11.4 88.6 Arnt and Schraube, Dissertation Techn. Hochschule, 

ox,, Berlin (1911). 

S5 Rhead and Wheeler, /. Chem. Soc. t 97, 2178 (1910). 

90.05 Bodmer, Dissertation Techn. Hochschule, 

13.85 86.15 Dent and Cobb (with graphite) Loc. cit. 

9.1 90.9 Dent and Cobb (with coke) Loc. cit. 

In the reaction between carbon and carbon dioxide the presence of water 
vapor affects the rate at which equilibrium is established as is often the 
case in many other reactions. A study of the effect of moisture on this 
reaction has been made by Topley 57 who shows that there is an approxi- 
mate proportionality between the concentration of water vapor and the rate 
of the reaction. 

For the production of carbon monoxide either in the pure condition or 
in low concentrations the reduction of carbon dioxide offers the cheapest 
and most convenient method of obtaining it. For producing pure carbon 
monoxide on a large scale it is usual to pass carbon dioxide and oxygen into 
a thick bed of coke heated to a high temperature. The reaction between the 
coke and carbon dioxide being endothermic and that between coke and 
oxygen being exothermic it is possible to control the temperature of the 
coke mass very accurately by the simple process of varying the quantity 
of carbon dioxide and oxygen admitted to the reaction. 

Action of Carbon Dioxide on Metals. The reduction of carbon 
dioxide with metals is a very common procedure and is often carried out 
in elementary laboratory work by chemical students. Producing the element 
carbon from solid carbon dioxide by burning aluminum or magnesium in 
a cavity made in a block of the solid is also a common and spectacular lec- 
ture demonstration experiment. It is possible, however, to control the 
experimental conditions so the reduction may go only part way and this 
is well illustrated by the reaction between metallic tin and carbon dioxide. 
The reaction is somewhat analogous to the carbon reduction and may be 
expressed as Sn+2CO 2 = SnO 2 +2CO. For theoretical reasons the reduc- 
tion of carbon dioxide by means of tin has received considerable study. 68 

The following equilibrium constants were found by Fraenkel and 
Snipischski : 

Temp.C. K Temp. C. K 

600 0.28 950 0.18 

650 0.27 1000 0.13 

700 0.27 1050 0.09 

750 0.26 1100 0.07 

800 0.25 1150 0.06 

850 023 1200 0.05 

900 022 

61 Topley, B. f Nature, 125, 560-1 (1930). 

"Fraenkel, W., and Snipischski, K. t Z. anorfi. allgem. Chem.. 125, 235-51 (1922). Maeda, 
Tratomu, Bull. Inst. Phys. Chcm ****.(**&) 2. 350-61 (1923). Eastman, E. D. f and Robinson, 
P., /. Am. Chcm. Soc., 50, 1106-14 (1928). Meyer, G., and Scheffer, F. E. ., Rec. trav. chim. 51. 
569-73 (1932). ' 



134 CARBON DIOXIDE 

These values were obtained by analyzing the gas mixture in equilibrium 
with tin at various temperatures and calculated from the expression 
K = Cco 2 /Cco where the concentrations were expressed in volume per cent. 

The best values of the equilibrium constant obtained by Eastman and 
Robinson were : 

Temp. C 650 700 750 800 850 900 

AT==C C02 /C CO 0.321 0.296 0277 0.260 0.245 0.232 

In a very recent work published by Meyer and Scheffer the values of 
Fraenkel and Snipischki at lower temperatures were confirmed but values 
above 800 C. were found to be too low. A good agreement was found, 
however, with the work of Eastman and Robinson. 

By treating carbon dioxide with metallic sodium or potassium it is 
possible to take the reduction down to salts of oxalic acid according to 
the general equation 2CO2 + M 2 = C2O 4 M2. Lemarchands and Roman 69 
have investigated this type of reduction and found that potassium produced 
a greater yield of the oxalate than was obtained with sodium. Thus at 
230 C. the potassium reacted with the carbon dioxide to an extent that 
yielded 17 per cent of oxalic acid. Sodium on the other hand, produced 
only 1.5 per cent oxalic acid when heated to 350 C. In this latter reaction 
the reduction goes principally to carbon. 

The Manufacture of Urea. The synthesis of urea is a question of 
sufficient commercial importance to justify its inclusion in the discussion of 
industrial uses of carbon dioxide, yet its chemistry is quite interesting and 
a brief mention of it here perhaps will not be out of place. Urea has 
recently become of considerable importance as a concentrated fertilizer 
and as a reagent in the rapidly growing field of organic plastics. It now 
seems not at all unreasonable to expect it to be one of the important concen- 
trated nitrogen carriers of the future. 

Carbon dioxide and ammonia under the proper conditions may react 
together to form ammonium carbamate and this compound on dehydration 
produces urea. The chemical reactions involved may be represented as 

f 110WS : C0 2 +2NH,= (NH 3 ),C0 2 

Ammonium carbamate 

and (NH 3 ) a CO a =(NH a ) 2 CO+H 2 

Urea 

The water liberated in the above reaction may also combine with some of 
the carbamate present to produce ammonium carbonate or ammonium bicar- 
bonate thus : 

(NH 3 ) a CO a +H a O=(NH 4 ) a CO a 
and (NH 4 ) a CO,=NH 4 HCO 8 +NH a 

The reactions involved in this system have received extensive study by 
many investigators who have treated them mostly from a phase point of 
view. Some of these investigations were made by Terres and Behrens, 60 

< Lemarchands, M. t and Roman, H. L., Compt. rend., 192, 1381-3 (1931). 
Terres, E., and Behrens, H., Z. physik. Client., Abt. A 139, 695-716 (1928). 



CHEMICAL PROPERTIES OF CARBON DIOXIDE 135 

Janecke, 61 Janecke and Rahlfs, 62 and Davis and Black. 63 A very careful 
and complete thermodynamic analysis was made by Klemenc 64 and the 
system studied from a practical point of view by Krase and his associ- 
ates. 65 

When anhydrous ammonia and anhydrous carbon dioxide arc mixed 
in the proportion of 2 moles of NII 3 to 1 mole of CO 2 and the mixture is 
then heated to 150 C. the resulting reaction will come to equilibrium when 
about 44 per cent of the carbamate first produced has been converted to 
urea. The conversion can be increased to 70 per cent at the same temper- 
ature if the molal ratio of ammonia to carbon dioxide is increased to 4 to 1. 
The yield of urea, while important, is perhaps of less importance than a 
complete recovery of the uncombined ammonia and carbon dioxide in the 
reaction mixture. This recovery can be made successfully and a unit for 
carrying it out becomes a part of any commercial plant. 

A very interesting description of an experimental plant, having a ten- 
ton ammonia input per day, is given by Krase, Gaddy and Clark. Their 
process uses liquid ammonia and liquid carbon dioxide in a reaction auto- 
clave and a conversion of 35 to 37 per cent can be obtained. The uncom- 
bined ammonia and carbon dioxide arc recovered from the discharge solu- 
tion and used over again. For the details of this interesting experimental 
work one is referred to the original paper of these investigators. 

Janecke, E., Z. Elektrochem., 35, 716-28 (1929). 
"Janecke, E., and Rahlfs, E., Z. Elcktrochcm., 36, 645-54 (1930). 
Davis, R. O. E., and Black, C. A., Ind. Eng. Chern., 23. 1280-82 (1931). 
"Klemenc, A., Z. anorg. allqem. Chcm., 191, 246-82 (1930). 

Krase, H. J., and Gaddy, V. L., /. Ind. Entj. Chem., 14, 611 (1922) ; /. Am. Chcm. Soc. t 52, 
3085 (1930). Krase, H. J., Gaddy, V. L, and Clark, K. G., Ind. Eng. Chem., 22, 289-93 (1930). 



Chapter V 
Carbon Dioxide and Vital Processes 

The fact that carbon dioxide is a product of the metabolic activity of 
animals and a food substance vital to the life of plants, makes it very 
closely related to all kinds of life. It is not surprising that many attempts 
have been made to determine the effect of increasing the normal carbon 
dioxide content of the atmosphere around growing plants or that numerous 
experiments have been conducted to determine the effect of this gas on 
animal life. These experiments have added considerably to our knowledge 
of vital processes and many of them have given results of some practical 
importance. 

Stimulating Plant Growth with Carbon Dioxide. Plant growth may 
be stimulated by increasing the concentration of carbon dioxide in the 
atmosphere around the leaves. This increase in growth rate is the result of 
the increased rate of diffusion of carbon dioxide through the stomata of the 
leaves caused by the increased concentration of the carbon dioxide sur- 
rounding them. Growth may also be stimulated indirectly by the action of 
carbon dioxide solution in ground water acting on soil materials with the 
liberation or formation of fertilizing materials necessary to plant life. It 
is evident that the former action gives promise of the most important results 
and it is in this field that most of the experimental work has been done. 

As one might expect, carbon dioxide is only one of the factors essential 
to plant growth and therefore a simple gassing of the plant with carbon 
dioxide may or may not increase its growth. The failure to recognize the 
importance of all other factors, except carbon dioxide concentration, lead 
some of the investigators in the beginning of this study to obtain negative 
results and for some time there was considerable debate as to whether 
increasing the carbon dioxide concentration of the atmosphere would actu- 
ally increase the rate of plant growth or not. However, modern investi- 
gators have demonstrated without the least doubt that with properly con- 
trolled conditions, plants will grow faster and larger and produce a greater 
crop yield when the carbon dioxide concentration is increased in the atmos- 
phere around the leaves. 

Many of these investigations have been conducted in closed boxes or in 
green houses where it was possible to control accurately the concentration 
of the carbon dioxide in the atmosphere. Field experiments have also been 
conducted on small plots as well as on very large tracts. Cummings and 
Jones 1 conducted experiments in inclosed boxes in which they were able to 
increase the carbon dioxide content of the gas. It was found by these 

1 Cummings, M. B., and Jones, C. H., Vermont Agr. Expt. Sta. Bull., 211, (1919). 

136 



CARBON DIOXIDE AND VITAL PROCESSES 137 

investigators that legumes showed an increase in production of pods and 
beans and that the chemical composition of the plant was slightly changed 
with the carbon dioxide treatment. Potatoes also showed an increase in 
yield of tubers and foilage. In these experiments, gassing the plants 
increased the hydrocarbon content and decreased the protein content. A 
little later, Fischer 2 published the results of experiments carried out on a 
large scale in the Ruhr coal region. The gas was furnished to large plots 
of land from the waste gases from Wast furnaces. These gases were puri- 
fied and distributed to the field in concrete pipes. A very large increase in 
production of potatoes was reported. Ranc 3 conducted his experiments in 
hothouses with potatoes, radishes, and tomatoes ; also some outside experi- 
ments with spinach, beets, potatoes, lupine and barley. In all cases, a 
greatly increased yield was obtained. Indications that interest in this 
subject is very much alive at present are shown by the many recent publi- 
cations dealing with it. 4 Jaccard 5 found that the consumption of carbon 
dioxide by a plant at constant illumination was a direct function of the 
temperature. Small and White obtained increased yields of tomatoes in 
greenhouse experiments with increased carbon dioxide concentration. 

The economic aspect of fertilizing growing plants with gaseous carbon 
dioxide is indeed an interesting one. Now that the fact is well established, 
that increasing the carbon dioxide concentration in the atmosphere around 
plants will actually increase growth and yield of product, the question 
naturally arises as to whether this can be clone at a profit. Riedel has 
emphasized this pliase of the question considerably and has devised methods 
of applying carbon dioxide to large tracts f land and to smaller inclosed 
spaces. Others have also treated the problem from a commercial point of 
view, but up to the present time there seems to be no possibility of success- 
fully gassing large tracts of growing plants. The question of economically 
treating plants with carbon dioxide in greenhouses may be an entirely differ- 
ent one, however. Here, of course, the cost of carbon dioxide and the ease of 
application are important factors. Commercial liquid carbon dioxide does 
not enter into this phase of the subject at all. Low grade carbon dioxide- 
air mixtures serve the purpose, and the methods of producing these usually 
depend upon the combustion of carbon containing materials such as alcohol, 
oil, coke, or upon the utilization of waste flue gases from certain industrial 
operations. 

Fischer, H., Z. angcn: Chcm. t 33, 197-8 (1920). 
"Ranc, A., Industrie Chimique, 7, 349-51 (1920). 

Bo1as, I. B. D., and Henderson, F. Y., Ann. Botany, 42, 509-24 (1928). Bornemann, Mitt. deut. 
Landwges., 1920. Ehrenberg. P., . Pflansenern'arh. Dumiung, B5, 85-6 (1926). Fischer, H. f Garten- 
flora, 61, 298-3CP; Zcntr. Biochcm. Biophys., 14, 487; Bcr. dcut. botan. Ges., 45, 331-9, (1927); 
Naturtvissenschaften, 8. 413-17 (1920); Angew. Botan., 1, 138-46 (1919). Gering, A., FuMintfs 
Landw. Ztg., 70. 137-53. 181-97 (1921). Hawkins, Florida Grower, 25, (1922). Heydemann, F., 
GartenbauurisfcnsclMft, 1, 100-40 (1928); E.rpt. Sta. Record, 60, 339-40. Janert, Heinz, Botan. 
archiv., 1, 155-76 (1922). Jess, /. a<?r. prat., 35. 229 (1921). Lundergardh, H., Annew Botan., 4, 
120-51 (1922). Reinan, E., Angeiv. Botan., 2, 290-302 (1920); Cliem.-Ztg.. 44, 808 (1920). Riedel, F-, 
Gartenwelt, 25, No. 31, 302-4; No. 34, 336-8 (1921); Exrt. Sta. Record, 45, 834; Chem.-Ztq. t 45. 829-30 
C1921); Gesundh-Ing., 53, 257-61 (1930). Schmidt, W., Fortsck. Landw., 4, 360 (1929). Schutte- 
Overbeck, Brcnnstoff-Chem., 11, 28-30 (1930). Wagner, H., Umschau, 27, 785-6 (1923). 

5 Jaccard, Paul, Bull. soc. chim. biol., 12, 156-70 (1930). 

8 Small, T. f and White, II. L., Ann. Applied Biol., 17, 81-9 (1930). 



138 CARBON DIOXIDE 

The Indirect Fertilization of Plants with Carbon Dioxide. Under 
this topic one might consider the action of various carbon dioxide-produc- 
ing reactions which take place in the soil, thus increasing the carbon dioxide 
in the soil air, and also in the air above the soil. Or one might consider 
the importance of the action of carbon dioxide-water solutions on the rock 
materials of the soil which liberate fertilizing materials necessary to plant 
growth. A short discussion of both of these phases will be given here. 

It is generally recognized that organic manures have a more favorable 
action as fertilizers than those not containing organic materials. It is 
thought that this added advantage may be due to the carbon dioxide liber- 
ated to the soil by the oxidation of the organic matter present. Whether 
this is entirely true or not, is somewhat doubtful. Bornemann 7 believes that 
part of this favorable action of dunged soil on plants may be due to the 
increased carbon dioxide produced. However, Gerlach's 8 experiments failed 
to confirm the idea and led this investigator to state that the only favorable 
.action of organic manures is due to the addition of nitrogen, potash and 
phosphoric acid to the soil. Yet Reinau 9 holds that the soil air must have 
considerable effect on the rate of plant growth. While one finds in the lit- 
erature many conflicting ideas on this subject, the fact yet remains that 
gassing plants with moderate amounts of carbon dioxide will increase the 
rate of growth and that organic manures do increase the carbon dioxide 
concentration of soil air. It therefore seems perfectly reasonable to expect 
at least some favorable action on plant growth due to this factor. 

In an attempt to increase the fertility of the soil, various so-called 
carbon dioxide fertilizers have been proposed and some attempts have been 
made to commercialize some of them. One such fertilizer, composed of 
peat, and charcoal, with small amounts of nitrogenous material, potash and 
phosphates, was investigated by Gerlach and Seidel 10 and was found ineffec- 
tive in increasing the yield of plant crops. Niklas, Scharrer and Strobel 11 
experimented with a mixture containing 50 per cent peat, 45 per cent char- 
coal and 5 per cent pyrolucite with negligible amounts of nutrient sub- 
stances. In 45 cylinder experiments, 23 showed definite increase in yield 
due to the fertilizer, while 18 showed no effect and 4 showed a decrease in 
yield. In 12 field experiments,. 7 gave increased yields and 5 showed no 
effect. Riede 12 also investigated "CO 2 -fertilizers" with practically no posi- 
tive results. 

The effect of carbonic acid solutions on rock material to liberate soluble 
potassium and phosphorous salts has already been discussed under the 
action of carbon dioxide on rocks. The importance of soil carbon dioxide 
in increasing the available nutrients in sufficient quantities to be of immedi- 
ate use to plants is somewhat doubtful. Vandecaveye 13 studied this phase 

T Bornemann, Mit. deut. Landwges., 1920. Biedermann's Zentr., 50, 296-9 (1921). 
Gerlach, Mitt, deut Landwges., 36, 147-50 (1921) ; Expt. Sta. Record, 46, 424. 

9 Reinau, E. H. f Festschr. Stoklasa, 1928, 305-18. 

10 Gerlach and Seidel, Z. Pflanxenernahr. DUn ff unff, B4, 241-7 (1925)). 

Niklas, H., Scharrer, K., and Strobel, A., Z. angew. Chern., 38, 251-8 (1925). 
u Riede, W., Z. Pflanscnernahr. D&ngung, 5, 383-5 (1926). 
Vandecaveye, S. C. f Soil Science, 16, 389-406 (1923). 



CARBON DIOXIDE AND VITAL PROCESSES 139 

of fertilization but discovered no relation between soil change and carbon 
dioxide production or the liberation of potassium salts. There was some 
indication, however, that a H-ion concentration less than pH 6 decreased 
the potassium adsorbing power of soil colloids. 

The Physiological Action of Carbon Dioxide on Animals. Probably 
no one subject connected with physiology has been treated in such an 
exhaustive manner as the physiological action of carbon dioxide. The lit- 
erature is filled with references to this important waste gas and the many 
ways that it affects body functioning. Here it will suffice to treat only a 
few phases of this subject and these only from the point of view of carbon 
dioxide utility and hazards connected with its presence in the air. 

Respiratory Stimulant. The carbon dioxide excreted through the 
lungs of animals acts as a definite regulator of breathing and insures a 
sufficient supply of oxygen to the system. This fact is of tremendous 
importance from a physiological point of view. The adjustment between 
expired carbon dioxide and depth and frequency of respiration are so delic- 
ately balanced that the slightest decrease or increase in the carbon dioxide 
production in the body, induces immediately an almost proportional increase 
or decrease of the volume of breathing. It seems reasonable, therefore, 
for one to be able, by artificially changing the carbon dioxide in the 
lungs, to control breathing to a certain extent. This control can actually 
be accomplished and to a much larger extent than might at first be expected. 
By voluntarily ventilating the lungs, thus decreasing the alveolar carbon 
dioxide, breathing can be suspended for a considerable time. On the other 
hand, the administration of carbon dioxide causes a considerable increase 
in the depth and frequency of respiration. Higher concentrations of car- 
bon dioxide than 25 to 30 per cent have a narcotic effect and tend to stop 
respiration even with a sufficient oxygen supply, but with a decreased 
oxygen supply, a very much lower concentration of carbon dioxide will 
depress breathing and even cause death. The response of normal individ- 
uals to the breathing of carbon dioxide-air mixtures is variable from person 
to person, and is not constant even with the same person at different times. 
The maximum increase in breathing is obtained with a 7 per cent carbon 
dioxide-air mixture. 14 From this point on, breathing is slowed down by 
increasing the carbon dioxide concentration. It has been found further 
that persons could work without decreased efficiency in a submarine if the 
carbon dioxide did not exceed 5 per cent. 15 The efficiency curve falls off 
rapidly, however, between 5.5 and 6 per cent. Six per cent is considered 
a critical point for men working and it is believed that the majority would 
be completely incapacitated in a short time in an atmosphere containing 
more than 6 per cent carbon dioxide. 

Lethal mixtures of carbon dioxide and air are hard to define exactly. 
Deaths have been reported as caused by widely varying concentrations. 

"Heller, E., Killiches, W., and Drinker, C. K., 7. Ind. Hyg., 11, 293-300 (1929). 
Brown, E. W., U. S. Naval Mcd. Bull.. 28, 721-733 (1930). 



140 CARBON DIOXIDE 

Thus an atmosphere showing 88 per cent nitrogen, 10.6 per cent carbon 
dioxide, and 1.4 per cent oxygen was responsible for the death of three men 
in a deep manhole. 10 In another case, four men were killed by jumping 
into a silo filled during the previous day with cut, immature corn. In five 
minutes each was dead or in a cyanotic condition from which he could 
not be revived. The air in the silo showed carbon dioxide 38 per cent, 
oxygen 13.5 per cent, and nitrogen 48.5 per cent. 17 Many examples of 
this type could be given but about the only conclusion one could draw 
from them is that the oxygen concentration perhaps plays a bigger part 
in the toxic properties of a gas mixture than does the presence of carbon 
dioxide. This can be shown by the results obtained by Schultzig. 18 He 
found no apparent evidence of carbon dioxide poisoning in a man exposed 
to an atmosphere containing 60 to 80 per cent carbon dioxide but with an 
adequate supply of oxygen; evidence of poisoning appeared, however, on 
exposure for fifty minutes to an atmosphere containing 9 to 9.5 per cent 
carbon dioxide with a deficient oxygen supply. 

Therapeutic Uses of Carbon Dioxide Gas. The application of carbon 
dioxide in therapeutics depends largely upon its property of acting as a 
respiratory stimulant. A gas mixture containing 5 per cent carbon dioxide 
and 95 per cent oxygen is sold under the trade name "carbogen" and this 
gas mixture is a standard remedy for carbon monoxide poisoning, drown- 
ing, shock, and as an aid in anesthesia and in the treatment in alkalosis. 

Drinker and Shaughnessy 19 suggest as a treatment for acute carbon 
monoxide poisoning a 7 per cent carbon dioxide-93 per cent oxygen mix- 
ture for the first 5 to 20 minutes followed by a 5 per cent carbon dioxide- 
95 per cent oxygen mixture. The use of pulmotors or any other positive 
pressure apparatus for the administration of this gas mixture is not favored 
at present. The usual method of administration is to furnish the gas to 
the patient by means of a device, such as an inhalator, and to promote 
respiration artificially, if necessary, by the prone pressure method. 

The use of carbon dioxide-oxygen mixtures for the induction and ter- 
mination of other anesthetics has now become widespread. Most modern 
mechanical devices designed to administer anesthetics, such as nitrous oxide, 
ethylene or ether, are fitted with carbon dioxide and oxygen cylinders and 
arranged so that various mixtures of these gases can be used if desired. It 
seems to be especially successful for terminating the anesthesia, and cases of 
post-operative pneumonia are rare where it has been used. 

Experiments conducted on dogs suffering with pneumonia indicate 
that carbon dioxide mixtures with oxygen may become valuable for reliev- 
ing a partial lung collapse. This collapse which seems to be a stage in 
pneumonia was quickly stopped and the lung redistended when carbon 
dioxide was administered. 20 

19 Tankard, A. R. f and Bagnal, D. J. T., Analyst, 55, 673-6 (1930). 
"Havhurst, E. R.. and Scott, E., J. Am. Med. Assoc., 63, 1570-2 (1914). 
"Schultzig, R., Arch. Hyg. 102, 366-90 (1929). 

"Drinker. C. K., and ShauRhncssy, J.. /. Ind. Ilyfl., II, 301-14 (1929). 

80 Henderson, Y., Haggard, H. W., Coryllos, P. N. Birnbaum, L., and Radloff, M. f Arch. 
Internal Med., 45, 72-91 (1930). ' 



CARBON DIOXIDE AND VITAL PROCESSES 141 

That carbon dioxide administration to insane patients has some tempo- 
rary beneficial effect has been demonstrated at the University of California 
Medical School. Experiments conducted with patients suffering with 
dementia praecox catatonia, showed that a fleeting return of intelligence 
was obtained when carbon dioxide was inhaled. These periods of sanity 
were brief, lasting from ten to fifteen minutes, but the patient was able to 
answer questions rationally, or to exhibit recognition of his surroundings. 
Whether any practical application of this information is possible, remains 
to be determined by further experimentation. 

The behavior of carbon dioxide as an anesthetic has been studied by 
Leake and Waters. 21 Dogs were successfully anesthetized in one minute 
with a mixture of 30 to 40 per cent carbon dioxide in oxygen. The anes- 
thesia seemed to become smoother and deeper the longer the animal 
remained under it. Dogs have been kept under the anesthetic for periods 
of time up to two hours. 

The treatment of hiccough with pure carbon dioxide is quite common. 
While it cannot be relied upon to effect a cure in all cases, numerous 
reports show that in certain types of hiccough it is a safe and reliable 
remedy. 22 

Whooping cough can also be treated with carbon dioxide and it is said 
that in many cases its administration was successful in decreasing the inten- 
sity and duration of the coughing spasms. 

Certain forms of infantile tetany have been treated with atmospheres 
containing excess carbon dioxide and in practically all cases a definite 
improvement was noticed. When a case failed to respond to all other 
methods of treatment, it was- exposed to a concentration of 40 per cent 
oxygen and the expired carbon dioxide was allowed to accumulate until 
it reached a concentration of 2 to 3 per cent. In 21 cases so treated, only 
one failed to improve with this treatment. 23 

The Use of Solid Carbon Dioxide as an Escharotic. The treatment of 
certain dermatologic affections with solidified carbon dioxide was first 
suggested by Dr. Pusey in Chicago in 1905. The efficiency of this thera- 
peutic agent was soon demonstrated and its use became quite widespread. 
Mechanical devices for the preparation of the solid from liquid carbon 
dioxide which could easily be obtained from commercial cylinders of the 
substance, were soon developed so the snow could be formed into pencils 
of the proper shape. However, the trouble necessary in preparing the 
snow just* before use, placed a serious handicap on this method of treatment 
and carbon dioxide gradually lost in competition with other therapeutic 
agents until today it is used but little for this purpose. Modern develop- 
ments in the commercialization of solid carbon dioxide should, however, 
materially decrease this handicap and it seems that the availability of solid 
carbon dioxide today should make it again a valuable escharotic. 

"Leake, C. D.. and Waters, R. M.. /. Pharmacot.. 33, 280-1 (1928). 

"Sheldon, R. F., Anesthesia and Analgesia, 6, 31-34 (1927). 

McCrea. E. F., and Raper, H. S., Univ. Manchester Quart. J. Med., 22, 269-79 (1929). 



142 CARBON DIOXIDE 

When solid carbon dioxide is pressed onto the skin, immediate freezing 
of the tissues in contact with the snow takes place, while the conduction of 
heat from below, gradually extends this freezing, deeper and deeper. The 
rate and depth of freezing depends entirely upon the pressure of the appli- 
cation and its time. The skin at the point of contact with the solid is con- 
siderably depressed, becomes very hard and white in color. After thawing, 
the skin regains its former level and in the course of a few minutes there 
results a well developed wheal. In mild freezings the damaged tissues are 
usually absorbed in a few days to a week without a crust or scar formation. 
More prolonged freezings usually result in a crust formation which disap- 
pears in about 10 days. In very serious freezings there may be a serum- 
like discharge, occasionally co-associated with pustular discharge where the 
lesion has been of the infective type, or has been secondarily infected, which 
continues for several days to a week with the formation of a decided scab. 
The scab often becomes black in color and remains from two to even six 
weeks after which it separates, leaving a very slight scar. The pain asso- 
ciated with solid carbon dioxide treatment is usually very slight, depending 
of course upon the place of application and the nature of previous treat- 
ments. Bernstein 24 gives a detailed account of many cases treated with 
solid carbon dioxide. A summary of his experience has been arranged in 
Table 64. 

Carbonated Baths. Carbonated baths, both natural and artificial, 
have enjoyed various degrees of popularity for many years. The idea 
originated in the naturally carbonated waters of Europe and much faith 
was at one time placed in these waters as therapeutic agents. That waters 
saturated with carbon dioxide have a decided physiological action on the 
skin can hardly be doubted, 25 yet the actual beneficial action is more or 
less vague. 

One of the most evident effects of carbon dioxide action is a reddening 
of the skin, a stimulation of circulation because of the dilation of the 
capillaries, a lowering of the blood pressure and a generally stimulated feel- 
ing. Experiments with dry baths of carbon dioxide conducted by Kimeto- 
wicz 26 gives one a good idea of its physiological action. The effects of dry 
carbon dioxide baths for 10 to 20 minutes at ordinary temperatures were: 
(1) The capillaries were dilated and the respiration was slowed. (2) The 
pressure in the brachial artery fell an average of 30 mm. from the maxi- 
mum. (3) The diastolic pulse, which by the ascillometer normally registered 
3.5 to 4, fell to 2.0 to 2.5. (5) The pulse rate was between 68 and 74 per 
minute. (6) The quantity of carbon dioxide in the atmosphere of the bath 
chamber increased during the bath from 0.1 to 0.5 per cent. (7) The quan- 
tity of carbon dioxide in the expired air of the subject was increased after 
a bath of 10 minutes from 3.7 to 5.0 per cent. (8) The respiratory volume 

* Bernstein, R.. "Solidified Carbon Dioxide," A. S. Aloe and Co., St. Louis, Mo. 

"Waledinsky, J. A., Z. phvsik. diatet. Therafne, 17, 18-26; Zentr. Biochem. Biophys., 14, 575. 
Hirschefeld, A., VerSffentlich. Zentralstelle BalneoL, (1912), No. 6; Zentr. Biochem. Biophyt., 13, 
447. Schott. A., Lancet, (1928), I, 546-8. 

Kitnetowicz, E., Compt. rend. soc. biol. t 95, 565-6 (1927). 



CARBON DIOXIDE AND VITAL PROCESSES 



143 



TABLE 64. Treatment of Skin Diseases by Freezing with Solid Carbon Dioxide. 



(According to Bernstein) 



Disease t: 

Acne Pustulosa 
Acne Indurata 
Acne Keloid 
Adenoma Sebaceum 
Angioma 
Naevus Vasculosus 

Telangiectasis 

Cavernous Angioma 
Angiokeratoma 

Callositas 

Carbuncle 

Chaloasma (liver spot) 
Clavus (corns) 
Colloid degeneration of 

the skin 

Cornu Cutaneum 
Dermatitis Repens 
Eczema 
Epithelioma 
Erythema Pernio (frost 

bite) 

Folliculitis Decalvans 
Hydrocystoma 
Keloid 

Keratosis Follicularis 
Lentigo (freckles) 
Leprosy 
Leukoplakia 
Lichen Planus 
Lupus Erythematosus 
Lymphangioma 

Milium 

Molluscum Contagiosum 

Morphea 

Naevus Pigmentosus 

Naevus Pilosus 

Naevus Lipomatodes 

Paget's Disease 

Psoriasis 

Rosacea 

Seborrhoea 

Steatoma 

Lupus Vulgaris 

Tuberculosis Verrucosa 

Scrofuloderma 

Ulcer (Chronic leg ulcer) 

Verruca Vulgaris (warts) 

Verruca Plana 

Verruca Filiformis 

Xanthoma Tuberosum 

Xeroderma Pigmentosum 

X-Ray Keratoses 



i ime 01 
eatment, 
sec. 


Pressure 
applied 


No. of 
cases 


Result of treatment 


5-10 


light 


numerous 


very successful 


10-15 


medium 





very successful 


15-20 


heavy 


2 


very successful 


10-15 


light 


1 


very successful 


10-30 


light 


_ 


several freezings 








successful 


20-30 


medium 


_ 


numerous freezings 








successful 


30-50 


heavy 


- 


successful 


30 


heavy 


1 


two treatments, 








successful 


60 


heavy 


_ 


several freezings, 








successful 


30-60 


medium 


several 


very successful 


10-20 


light 


numerous 


very successful 


60 


heavy 





very successful 


30- 


medium 


1 


very successful 


30 


medium 


2 


very successful 


20 


medium 


1 


very successful 


5-20 


medium 


2 


very successful 


30-60 


heavy 


numerous 


very successful 


5-10 


light 


1 


very successful 


10 


medium 


1 


successful 


15 


medium 


1 


successful 


60 


heavy 


3 


successful 


20 


medium 


1 


successful 


10 


light 


- 


successful 


30-60 


heavy 





helpful 


10 


medium 


1 


doubtful 


15 


medium 


2 


helpful 


20-40 


medium 


many 


very successful 


45 


heavy 


1 


many treatments 








were successful 


10 


medium 


2 


successful 


40-60 


heavy 


4 


successful 


15 


light 


1 


successful 


10 


light 





successful 


20 


medium 


_ 


successful 


45 


heavy 


- 


successful 


60 


heavy 


2 


many treatments 








were successful 


10-15 


medium 


2 


helpful 


15-20 


medium 


1 


fair success 


3CM5 


heavy 


_ 


successful 


30-60 


heavy 


2 


successful 


60 


heavy 


2 


successful 


60 


heavy 


1 


doubtful 


60 


heavy 


1 


successful 


15 


light 





successful 


45-60 


heavy 


_ 


successful 


30-45 


heavy 


_ 


successful 


20-30 


light 


_. 


successful 


45-60 


heavy 


2 


successful 


20-30 


medium 


1 


successful 


45-60 


heavy 


- 


successful 



144 CARBON DIOXIDE 

measured by the spirometer was raised from 80 liters during 10 minutes 
before the bath to 103 liters during 10 minutes of the bath. 
x Carbon Dioxide as an Insecticide. The action of carbon dioxide as 
an insecticide may be utilized in several different ways. First it may be 
used as a source of power for projecting liquid sprays onto trees or shrubs ; 
second, it serves as a respiratory stimulant to make poisonous gases more 
effective ; and third, it may be used as a fumigating gas. 

Armet 27 advocated the use of carbon dioxide in place of compressed air 
in spraying devices. It was claimed that the use of carbon dioxide tended 
to promote thorough mixing and better subdivision of the spray because of 
the evolution of the dissolved gas. It was also thought that at the same 
time it exerted a solvent action upon the basic copper sulfate of Bordeaux 
mixtures and a beneficial effect on the foliage. 

Regardless of the specific advantage of carbon dioxide as such, it cer- 
tainly has an advantage as a detached power source. This is especially true 
where small units of spraying equipment are used and where the use of a 
more expensive air compressor would be uneconomical. 

The mixing of carbon dioxide with gaseous insecticides has been found 
especially advantageous as it permits a reduction in both dosage and 
exposure time. 28 The action on the insect is well illustrated by means of 
the American cockroach (Periplancta americana) . When at rest, at room 
temperature, this insect displays no respiratory movements and its tracheal 
valves are nearly closed. If it is brought into an atmosphere containing 2 
or 3 per cent carbon dioxide, the valves open immediately, allowing a more 
rapid diffusion of respiratory gases. When the carbon dioxide concentra- 
tion is brought to 7 or 10 per cent, respiratory movements of the abdomen 
appear. The width of the spiracle opening is therefore regulated by the 
concentration of carbon dioxide in the vicinity of the spii acle. 29 

In the fumigation of food materials carbon dioxide holds an important 
place. One of the most important grain fumigants is ethylene oxide and 
carbon dioxide. This gas mixture is practically 100 per cenc efficient, when 
properly applied, against the grain weevil, even at winter temperatures. 
The compounds are mixed in the proportion of 10 pounds of carbon dioxide 
(preferably in the form of solid carbon dioxide) to 1 pound of ethylene 
oxide. Thirty-three pounds of this mixture is added to 1000 bushels of 
grain. The process of applying this gas, consists of mixing the ethylene 
oxide and solid carbon dioxide together in large pails and introducing the 
mixture into the grain as it is being run into the bin, the mixture being 
carried down with the grain and well distributed through it. No odor of 
chemicals is left in the grain by these compounds. 30 

Second only in importance to the stimulation of respiration in insects, 
is the property of carbon dioxide to reduce the fire hazard when mixed with 

w Armet, H., Prog. agr. rit., 81, 592-7 (1924); ibid., 82, 88-96 (1924). 

"Cotton, R. T., and Young, II. D.. Proc. Entomol. Soc. Washington, 31, 97-102 (1929). 

Hazelhoff, E. H., 7. Econ. Entomol., 21, 790 (1928). 

Back, E. A.. Cotton, R. T., Youn ff . H. D., and Cox, J. H.. U. S. Dept. Afir. Bur. Entomol., 
(1930). Russ. J. M., Ind. Eng. Chem.. 22, 328-332 (1930). Fleck. W., Anal. soc. rur. Argentina, 
73 (1931). Osburn, M. R., /. N. Y. Entomol. Soc., 39, 567 (193lJ. 



CARBON DIOXIDE AND VITAL PROCESSES 145 

inflammable fumigants. This is especially true when ethylene oxide is used 
for this purpose. When mixed in the proportion indicated above, the fire 
hazard is reduced practically to zero. The inflammability of carbon dioxide 
and ethylene oxide mixtures has been studied by Jones and Kennedy, 31 
who found mixtures consisting of 1 pound of ethylene oxide to 7.5 pounds 
of carbon dioxide were uninflammable under normal conditions of tempera- 
ture and pressure. The same investigators 32 also found that when ethylene 
dichloride was used as a fumigant, 1.25 pound of carbon dioxide per pound 
of ethylene dichloride made the mixture non-inflammable. 

The use of carbon dioxide directly as a fumigant is perhaps of little 
importance. A method for fur preservation suggested by Tiepolt is inter- 
esting and practical. The furs are placed in a gas-tight container and a 
block of dry ice placed near them. The cold produced drives the moths 
away and the cold gaseous carbon dioxide falls to the bottom and gradually 
fills the container with an atmosphere in which no moth or other living 
organism can survive. 

"Jones, G. W., and Kennedy, R. E. f Ind. Eng. Chem, 22, 146-7 (1930). 
"Jones, G. W. t and Kennedy, R. E., Ind. Eng. Chem., 22, 963-4 (1930). 



Chapter VI 

Commercial Manufacture of Liquid 
Carbon Dioxide 

v THE COKE OR ABSORPTION PROCESS 

In the coke or absorption process for manufacturing liquid or solid 
carbon dioxide the raw gas on which the process operates is ordinarily 
made by the combustion of coke. The process, however, is fundamentally 
a method of purification or carbon dioxide separation from other gases by 
means of absorption and it is by no means confined to a gas produced in 
the above manner. As a matter of fact any gas reasonably free from dust, 
sulfur dioxide and gaseous hydrocarbons but containing carbon dioxide in 
sufficient concentrations can be treated by the absorption process for the 
removal of a fraction of its carbon dioxide content. Because of the limita- 
tions of the absorbing apparatus ordinarily used, such gas mixtures should 
contain carbon dioxide in concentrations at least from 10 to 15 per cent. 
The flue gases obtained from ordinary coal-fired furnaces uo not meet the 
above requirements sufficiently to make them of murh commercial value 
although in some cases coal is being used in small amounts for c< mbustion 
in carbon dioxide plants. 

f The absorption process in general consists of the following steps: 
(1) The production of a gas containing carbon dioxide. (2) The purifi- 
cation of this gas by scrubbing with water, dilute sodium carbonate solution 
or both. (3) The absorption of a part of the carbon dioxide in an alkaline 
solution of sodium carbonate, potassium carbonate or monoethanolamine. 
(4) The liberation of the pure carbon dioxide from the absorbing agent 
by boiling. (5) The condensation and separation of water from the gas. 
(6) The drying and compression of the purified carbon dioxide. (7) The 
condensation of the gas to a liquid and then charging it into steel cylin- 
ders for shipment or converting it into the solid state. The following 
description of these operations must of necessity be a composite picture of 
the present industrial plants. No uniformity in equipment is found except 
in cases where several plants are under one management. 

The Furnace. Boiler and furnace equipment in carbon dioxide plants 
does not differ to any considerable extent from that found in other indus- 
trial power installations. A surprising number of plants uses ijand-firfid 
furnaces but the advantage gained by the close supervision of the fuel bed 
offsets to a considerable extent the loss occasioned by admitting air over 
the fuel from "time to time. 

146 



MANUFACTURE OP LIQUID CARBON DIOXIDE ;;I47 

Methods of calculating boiler capacities and grate sizes do tidT differ 
much from those used for coal-fired furnaces. For h^nd-fif^d rfgfcnaces, a 
grate area of 1 square foot for 7 pounds of coke consumed per hour is not 
far from, the average. 1 Where conditions allow, increasing the grate sur- 
face over this figure permits lower operating temperatures and economy in 
furnace repairs. Assuming a plant to be designed for a capacity of 1000 
pounds of liquid carbon dioxide per hour and with a recovery ratio of one 
pound of coke to each pound of carbon dioxide recovered (most plants do 
considerably better than this) then for 1000 pounds of coke consumed each 
hour a total grate area of about 143 square feet would be required. As a fair 
grade of coke will evaporate about 10 pounds of water from and at 212 F. 
per pound of coke burned the resulting boiler horse-power would be about 
290. Such a heating plant could be conveniently divided into three furnaces 
with 100 horse-power boilers over each. 

Where automatic stokers are used somewhat smaller grate areas are 
permitted. Also an auxiliary blower may be used for recharging some of 
the flue gas back into the furnace to effect a more complete mixing of the 
combustion gases. Higher possible carbon dioxide concentrations are 
claimed for this arrangement. 

S Heat exchangers or "economizers" attached to the flues of coke furnaces 
may be used for heating boiler feed water or heating the strong lye on its 
way to the lye boiler. The latter arrangement is to be preferred, however, 
as most of the feed water comes directly from the heating coils in the lye 
boiler and at a temperature not far below its boiling point (in one plant at 
90 C. or 194 F.). The flue gases leaving the economizer cart be brought 
to a temperature near 170 C. or 338 F. 

Draft for the furnaces is usually obtained by a blower located between 
the scrubbers and the coke towers. This fan can be operated by means of 
a steam engine, the throttle of which is automatically controlled by the 
steam pressure in the steam boiler. 

S Fuel. The fuel used in a carbon dioxide plant is an important factor. 
A good grade of foundry coke gives the best results but this is not 
always obtainable at a reasonable price. Such coke may be 48-hour or 
72-hour, the latter being preferred. By-product coke from an artificial 
gas plant is sometimes used but it is not entirely satisfactory. Coal is 
being used in some pla-nts to a small extent but the authors know of no 
plant where it is used exclusively. The use of natural gas would seem 
to offer a solution to the fuel problem but the carbon dioxide- concentra- 
tion in such a flue gas is low and its use results in a decrease of plant 
capacity. The sulfur content of any fuel used must be very low other- 
wise the sulfur dioxide formed during its combustion contaminates the 
flue gas seriously and unless this is all removed it is taken* up by the 
alkaline solution in the absorbing tower thus decreasing its absorbing 
capaqity. 

1 See Nicol, E. W. L., "Coke and Its Uses," Ernest Benn. Ltd., London (W23]L 



148 CARBON DIOXIDE 

Chemistry of Combustion. The chemical reactions involved in the 
combustion of coke are quite simple and perhaps some of the theoretical 
and practical aspects of this operation may lie given here to an advantage. 

As the primary air for the combustion of coke enters the bottom layer 
of the highly heated fuel, its oxygen combines with the carbon of the coke 
according to the following equation: C+O 2 = CO 2 + 97,000 calories. This 
carbon dioxide, passing up through the mass of heated carbon, may then be 
partly reduced to carbon monoxide, according to- the equation: CC>2-hC = 
2CO 39,000 calories. Other secondary reactions may also take place, such 
as the direct combination of carbon with oxygen, to produce carbon monox- 
ide and the reduction of water vapor which enters the furnace as moisture 
in the air or in the coke. It is evident at once that it should be the aim of 
the operator to promote the first reaction and to prevent as far as possible 
all secondary reactions which produce compounds other than carbon 
dioxide. Air is usually admitted over the top of the coke mass to complete, 
by secondary combustion, the burning of the carbon monoxide. This reac- 
tion is usually not complete so one may expect a small amount of carbon 
monoxide in the gaseous products of any coke fire. It stands to reason, 
however, while the quantity of carbon monoxide should be kept just as low 
as possible, excess air should not be added in sufficient quantities to 
decrease the per cent of carbon dioxide in the flue gas. If all of the oxygen 
in the air could be made to combine with coke to produce carbon dioxide, 
a flue gas of 20.9 per cent carbon dioxide would result. Practically, this 
is not possible, and a flue gas of about 17 to 18 per cent is the best that can 
be expected. However, to keep the flue gas up to this concentration requires 
much care and considerable experience in firing a coke furnace. 

The factors which affect the per cent of carbon dioxide in a flue gas 
from a coke furnace are : first the depth of the fuel bed, second the flow ot 
air to the furnace, together with the admission of secondary air over the 
fire, and third the temperature of the fire. The first factor can be readily 
controlled by proper firing. The second, however, depends upon the speed 
of the draft fan and in many plants this is automatically controlled by the 
steam consumption. The temperature of the fire is also somewhat of a 
fixed character as it is more or less determined by the design of the furnace. 
f* Figure 30 shows in graphical form the results obtained by analyzing 
the gases in a coke mass at various points above the grate. 2 These curves 
show at a glance the conditions necessary for producing the maximum per- 
centage of carbon dioxide. First, the fuel bed should not be above the 
height indicated at the inflexion point. The evaluation of this height in cen- 
timeters or inches is not possible from the diagram but can be determined, 
in most cases, with sufficient accuracy by experience with the furnace in 
question. It should be noted that a depth slightly below that indicated by 
the inflexion point would give a lower carbon monoxide concentration 
while affecting the carbon dioxide concentration but slightly. An increase 

From Walker, Lewis and Me Adams. '^Principles of Chemical Engineering," McGraw-Hill 
Book Co., New York. Based on data of Kreisinger, Ovitz and Augustine, U. S. Bureau Mines, 
Tech. Paper. 137 (1917). 



MANUFACTURE OF LIQUID CARBON DIOXIDE 



149 



in gas velocity increases the carbon dioxide and decreases the carbon mon- 
oxide but this factor, as has already been mentioned, is not subject to direct 
control. Perhaps next to the fuel depth, the temperature of the coke is the 
next important factor. High temperatures increase the carbon monoxide 
concentration and decrease the carbon dioxide content, therefore the grate 
area should be sufficiently large to maintain a moderate temperature and 
yet produce sufficient heat for the plant requirements. The combination of 
oxygen with carbon, to produce carbon dioxide, starts at a temperature 
between 600 and 800 C. (1112 and 1472 F.). Increasing the temper- 
ature above this point, raises the carbon monoxide content of the flue gas 
needlessly. 3 



Rise at high temperature 
CO asymptote* equilibrium 



C0 t asymptote equilibrium 
Fall* at high temperature 




Abscissae . distance above grate bar* up through the solid fuel bed 



FIGURE 30. The Change in Gas Composition at Various Points 
Above the Grate in a Coke Fire. 

The widespread use of natural gas as an industrial fuel naturally leads 
to the question of its application to the carbon dioxide industry. At first 
glance, it would appear to be an ideal fuel, furnishing a flue gas of excep- 
tional purity without the presence of dust or sulfur dioxide. Much of the 
natural gas of Texas, Oklahoma and Wyoming is practically pure methane 
which would burn to carbon dioxide and water according to the equation : 

CH 4 +2O a =CO a +2H a O. 

The oxygen necessary therefore for burning one volume of this gas would 
be furnished by 9.5 volumes of air and the carbon dioxide in the resulting 
combustion gas would be about 11.8 per cent if all of the water produced, 
was condensed. This theoretical maximum carbon dioxide concentration 
for the combustion products of natural gas, compares quite unfavorably 
with the value of 21 per cent from burning coke. In spite of its unfavor- 
able characteristics, however, natural gas is being used more and more for 
this purpose. At the present time the authors know of two carbon dioxide 
plants in Los Angeles, California, that are making use of it and Goosmann 4 

1 Some of the newer types of furnaces operate at a temperature of 1400 C. (2552 F.) and 
above, and the carbon monoxide concentration is decreased by recirculation of part of the flue gas 
through the combustion zone. 

4 Goosmann, J. C., Ice and Refrigeration, 79, 397-401 (1930). 



ISO 



CARBON DIOXIDE 



refers to a plant in Texas that operates with natural gas with very satisfac- 
tory results. The flue gas in this plant, however, hardly ever exceeds 10.5 
per cent. 

win all carbon dioxide plants the flue gases are moved through the system 
by means of fans or blowers. These blowers are often located in the line 
directly after the scrubbing system and are, in many cases, connected with 
an engine the speed of which can be adjusted to produce just the right 
draft on the furnaces. Automatic devices can be and are sometimes used 
to regulate the speed of the blower engine and thus hold the steam pressure 
at a constant value. 

y Scrubbers. The simplest type of scrubber is a tower or tank made of 
steel, concrete or wood, and packed with small pieces of limestone. Water 
from the condensing system is flowed over the packing by means of a speci- 
ally arranged spreader at the top of the tower. The sulfurous acid produced 



Water from Gondnsr 




FIGURE 31. Limestone Scrubbers for Removing Sulfur 
Dioxide from the Flue Gas. 

by water and sulfur dioxide in the flue gas as it rises through this rock pack- 
ing, reacts with the calcium carbonate, producing carbon dioxide and calcium 
acid sulfite. The soluble calcium acid sulfite thus produced, is washed out 
of the tower with the waste water, while the carbon dioxide goes into the 
gas stream. This reaction decreases the volume of the limestone packing 
very slowly and as it settles it is only necessary to add more to the top to 
keep the scrubbers in perfect operating condition. A diagram of such a 
scrubbing system is shown in Figure 31. 

A scrubbing system consisting of two scrubbers 5 ft. internal diameter 
by 8 ft. high, with a flue gas flow of 200 cu. ft. per min. and a water flow 
of 20 gals, per min. to each scrubber, when tested showed that 88.7 per 
cent of the total sulfur dioxide was removed from the flue gas. The first 
scrubber removed 85.2 per cent of this amount and the second removed 
the rest. The 11.3 per cent of the sulfur dioxide remaining in the flue gas 



MANUFACTURE OF LIQUID CARBON DIOXIDE 151 

passed into the absorber where it reacted with the alkaline solution thus 
decreasing its efficiency. 

The use of a dilute solution of sodium carbonate as a scrubbing liquid 
was suggested by Luhmann 5 in 1917. A number of important carbon 
dioxide plants now use scrubbing systems consisting of a coke-packed tower 
with water as the washing agent and in series with this a similar tower 
with a solution of sodium carbonate and bicarbonate as the scrubbing med- 
ium. The wash water from the first tower is run to waste but the solution 
of soda lye from the second is recirculatcd by means of a pump and is only 
discarded when the sulfatc concentration becomes high enough to make 
further use unprofitable. 

VAbsorption. This operation is, of course, considered of great import- ' 
ance in the production of carbon dioxide. At the point where absorption 
takes place that carbon dioxide which is eventually compressed into cylin- 
ders, and that which goes out into the atmosphere as waste gas, are separ- 
ated. Naturally anything which prevents this unit from operating at maxi- 
mum efficiency is reflected at once on the capacity of the plant and for this 
reason this operation and the equally important process, the lye boiling, is 
closely watched. 

The absorption of carbon dioxide in potassium carbonate, sodium car- 
bonate or monoethanolamine is a continuous process conducted in a counter- 
current absorbing tower or a series of such towers. In nearly all cases 
these towers are packed with coke over which the absorbing liquid is 
pumped while the flue gas passes from the bottom upwards. Experience 
has shown that this arrangement gives good results and while its efficiency 
is not high, its simplicity, lack of back pressure and cheapness of construc- 
tion, as well as operation, makes it the almost universally used absorber for 
this purpose. In the past most absorbing units have been designed with 
but little real engineering data to work on. Capacities have been estimated 
from the observed behavior of other units already in operation and in 
general it has been, more or less, a hit or miss proposition. Recently, 
thanks to the investigators working in this field, much information has 
been gained and many data collected which put the whole question on a 
more rational basis, but even yet it cannot be said that exact computations 
of coke tower design and operation can be made. 

^Absorption in Water. The absorption of moderately soluble gases in 
liquids in which no new chemical substance is formed is a case of simple 
solution and the relations between the solute and the solvent are expressed 
rather closely, in most cases, by Henry's law. The usual mathematical 
equation expressing this law is, W=Kp where W is the weight of gas dis- 
solved under the partial pressure p and K is the proportionality constant. 
Where the above relationship holds, the rate at which this absorption tends 
to come to equilibrium, under isothermal conditions, depends upon a number 
of factors such as surface area of liquid, the difference in concentration of 

Luhmann, Z. ges. Koklensaurcind., 23, 471-2, 483-6 (1917). 



152 CARBON DIOXIDE 

the gas in the vapor and the liquid phases and the specific characteristics 
of the solute and solvent. The specific characteristics of the solute and 
solvent change with the temperature in such a way that the value of K 
decreases with an increase in temperature. The nature of this decrease, 
however, cannot always be predicted and the values of K are best deter- 
mined experimentally. In the case of carbon dioxide and water Henry's 
law is valid at low pressures i. e. from 1 atmosphere down to 1/20,000 
atmosphere, therefore the validity of the law may be assumed for all condi- 
tions affecting ordinary absorption processes. 

Commercially the use of a pure liquid, such as water, is not as important 
as the use of an alkaline carbonate as an absorbing agent. In some plants 
carbon monoxide obtained from carbide furnaces is partially oxidized with 
steam to carbon dioxide and the resulting mixture of carbon dioxide, carbon 
monoxide and hydrogen is treated in an absorber of the pressure type for 
the removal of the carbon dioxide. The water solution of carbon dioxide 
thus obtained readily gives up its carbon dioxide when the pressure is 
decreased. The separated carbon monoxide and hydrogen, after some puri- 
fication, are then passed into a catalyst chamber where they are converted 
into methanol. 

Water absorption of carbon dioxide from air mixtures or from flue 
gases 7 cannot be so successfully accomplished, however. In the case of the 
carbon monoxide, hydrogen and carbon dioxide mixture, where the sepa- 
rated carbon dioxide is apt to be contaminated with hydrogen and carbon 
monoxide, the purification is easily accomplished by the simple oxidation of 
the impurities to carbon dioxide and water. On the other hand, when nitro- 
gen is one of the impurities its removal becomes a very difficult matter and 
this purification process is one that cannot be readily adapted to commercial 
conditions unless the ordinary lye absorption process is employed. 

>/ Absorption in Triethanolamine Solution. A few years ago there 
appeared a new process for absorbing carbon dioxide which gave indications 
that a very radical change in carbon dioxide absorption was about to take 
place. This process made use of an organic absorbing agent having the 
chemical name of triethanolamine. As one might expect trade names have 
already been applied with the object of making it somewhat easier to say. 
The process of absorbing carbon dioxide in triethanolamine was of course 
patented and the compound itself put on the market. 8 During the process 
of commercial development it was discovered, as is often the case, that the 
economics of the reaction is of more importance than its chemistry and 
triethanolamine has not made the startling changes in the art of carbon 
dioxide manufacture that was at first predicted. As a matter of fact this 
absorbing agent is of practically no commercial importance at the present 
time but its chemistry is so interesting it may deserve a little space here. 

Buch, Nord. Kemistmotet (Finland), 184-92 (1928). 

'Heirich, C., Z. kompr. flits* Case, 22, 3-7, 21-2, 43-4 (1922). 

Carbide and Carbon Chemicals Corporation. "Triethanolamine" July 1, 1930. 



MANUFACTURE OF LIQUID CARBON DIOXIDE 153 

Monoethanolamine is also a good absorbing agent for carbon dioxide 
and at least one commercial plant is using it for this purpose. This is a 
moderately sized plant of about 500 pounds of carbon dioxide per hour 
which originally operated with triethanolamine. It is reported that excellent 
results are obtained with this absorbent. The chemistry of absorption is 
essentially the same for both these compounds and the reactions for the 
triethanolamine absorption will be discussed. 

This absorption process makes use of a concentrated water solution 
(about 50 per cent) of triethanolamine carbonate (triethanolammonium 
carbonate) which is formed as the first product in the reaction of carbon 
dioxide in a triethanolamine solution. 

2N(C 2 H 4 OH), + H a O + C0 a > ((N(C 2 H 4 OH) a H)),CO, 

Triethanolamine Water Carbon dioxide Triethanolamine carbonate 

The absorber consists of a scrubbing tower containing the carbonate solu- 
tion through which the gas is passed counter-current to the liquid flow. A 
temperature is maintained around 20 to 30 C. and the carbon dioxide 
reacts with triethanolamine carbonate to form the acid salt as follows : 

[(N(C 2 H 4 OH) 3 H)] 2 C0 3 + H a O + CO a *=* 2[(N(C 2 H 4 OH) 8 H)]HCO, 
Triethanolamine carbonate Water Carbon dioxide Triethanolamine bicarbonate 

The solution of this triethanolamine bicarbonate is passed into a regenerator 
and heated to the boiling point, 100 to 110 C., whereupon carbon dioxide 
is quantitatively released and the neutral carbonate regenerated. 

An inspection of this reversible reaction shows that, in the form of the 
neutral carbonate, 6.77 pounds of triethanolamine can absorb and release 1 
pound of carbon dioxide, or 1 volume of triethanolamine can absorb and 
release 90 volumes of carbon dioxide at 20 C. and 1 atmosphere pressure. 
The factor which determines the actual volume of carbon dioxide gas 
absorbed per unit volume of carbonate solution is the partial pressure of 
gas over the bicarbonate solution. Absorption will continue until the carbon 
dioxide pressure above this solution equals that of the incoming gas, so that 
the process is increasingly efficient with higher carbon dioxide concentra- 
tions in the gas to be purified and with lower scrubbing temperatures. In 
practice the concentration of carbon dioxide can be reduced efficiently by 
counter-current scrubbing to less than 1 per cent. 

In the regeneration stage, carbon dioxide begins to be evolved around 
60 C. and the speed of evolution increases with rising temperature up to 
the boiling point of the solution. Since little water is distilled, the heat 
consumption in this stage is comparatively low. 

V' Absorption in Solutions of Alkali Carbonates. A satisfactory sepa- 
ration of carbon dioxide from gas mixtures can be made with an absorb- 
ing liquid containing certain inorganic compounds with which the carbon 
dioxide combines loosely and from which it can be again separated when 
placed under a new set of conditions. In practical operations either sodium 



154 CARBON DIOXIDE 

carbonate or potassium carbonate is used for this purpose and while the 
efficiency of the operation is not high it has certain advantages over other 
absorbing solutions. The use of a solvent containing both of these alkali 
carbonates has been advocated 9 because of the greater concentration pos- 
sible and the consequent increase in absorbing capacity. No information is 
available, however, concerning the commercial application of this idea. 
The potassium compound produces a bicarbonate which is more soluble 
than the corresponding sodium compound thus making it a more efficient 
absorbing agent than the sodium salt. 

The temperature of the lye solution used for absorbing carbon dioxide 
is important. In general the lye stream is held between 30 and 40 C. and 
in order to keep it at this temperature special water coolers are required. 

Equilibrium Relations in Absorption Systems. The success of ttyt 
absorption and desorption of carbon dioxide in a solution of alkali carbonate 
depends upon the reversibility of the following equation : 

Na a CO 3 -h H a O + CO a *=5 2NaHCO 3 . 

In general it may be considered that this reaction tends to go towards the 
right at low temperatures and towards the left at elevated temperatures. 
Certain other factors influence the equilibrium, however, in such a way that 
the degree of shift in equilibrium cannot be easily predicted. 

The equilibrium relations in the above equation were studied some years 
ago by McCoy 10 in sodium carbonate solutions of concentrations from 0.1 
to 1.0 N and from the resulting data he derived the following equation: 

2/2 AT 
.7-7! k (45) 



In this equation / is the fraction of sodium present as bicarbonate, (I/) 
the fraction of sodium present as carbonate, N the normality of solution 
with respect to the base, K the mass action constant which varies with the 
concentration and the temperature, z the solubility coefficient of carbon 
dioxide in water expressed as moles per liter and />co2 the partial pressure 
of carbon dioxide in the gas phase. This equation seems to hold with 
considerable accuracy under the conditions used for obtaining the data. It 
is unfortunate, however, that the experiments were not carried out in more 
concentrated solutions and with a wider range of temperatures and carbon 
dioxide pressures in order that the results could be more easily applied to 
practical operating conditions. The general applicability of this equation, 
nevertheless, is now pretty well accepted even at higher concentrations of 
alkali and carbon dioxide. 

Walker, Bray and Johnston 11 have also made a very careful study of 
the equilibrium conditions in a system containing sodium carbonate, sodium 
bicarbonate and carbon dioxide as well as the corresponding system in 

Tomlinson, G. H., Can. Chcm. /., 4, 189-90 (1920). 

10 McCoy, H. N. f Am. Chcm. /., 29, 437 (1903). 

11 Walker, A. C., Bray, U. 8., and Johnston, J. /. Am. Chcm. Soc. t 49, 1235 (1927). 



MANUFACTURE OF LIQUID CARBON DIOXIDE 155 

which potassium was the alkali metal. The partial pressure of carbon diox- 
ide used by these investigators, however, was practically the same as that 
found in the air and this fact makes their results difficult to apply to the 
conditions found in a commercial carbon dioxide absorber. 

The work best fitted to show the conditions in a coke tower, where 
equilibrium is reached, was published by Sieverts and Fritzsche 12 in 1924. 
These investigators used potash solutions of about 2 N with respect to the 
potassium, the carbon dioxide concentration was varied over a wide range 
and their temperatures covered pretty well the whole field as it is used in 
practice. The expression representing the equilibrium relations as given 
by these investigators is, 

a2 [KHCOJ2 760 

............ (46) 



where a is the per cent dissociation of KHCO 3 , 3 the per cent dissociation 
of K 2 CO 3 . Y is the degree of hydration of the CO 2 , [KHCO 3 ] is the molar 
concentration of the bicarbonate and [K 2 CO 3 ] is the molar concentration 
of the carbonate. 

This expression can be simplified somewhat because it has been demon- 
strated that the ratio of ct 2 /3 is independent of the concentration of the 
alkali, also the solubility of carbon dioxide z and therefore Y the degree of 
hydration will remain constant at any one temperature. The above equa- 
tion then becomes : 

[KHCOJ2 
--- - - =k ............. (47) 

[K 2 C0 3 U :02 

or it may be written in a more convenient form as : 

= k ............. (48) 

-/>co 2 

which is, of course, the same as McCoy's equation. Sieverts and Fritzsche 
have determined the values for k at a number of different temperatures and 
have found a remarkable agreement between them under isothermal condi- 
tions, even when the partial pressure of carbon dioxide was varied over a 
very wide range. These values when plotted on large scale cross section 
paper, yielded a curve from which the values of k indicated in Table 65 
were read. 

In most cases the plant operator is interested in only two phases of 
this problem, the first is to keep the concentration of the bicarbonate as 
high as possible in the strong lye coming from the coke tower, and the 
second is to keep it as low as possible in the lye coming from the lye boiler. 
In order to bring about these conditions he knows that a high tempera- 
ture is needed in the lye boiler and a much lower temperature in the coke 
tower. The relation between these variables is clearly indicated in Table 65 

u Sieverts, A., and Fritzsche, A., Z. anorg. all gem. Chcm., 133, 1-16 (1924). 



156 CARBON DIOXIDE 

TABLE 65. Showing the Relation Between the Tempera- 

ture, Bicarbonate and Carbonate Concentrations Under 

Equilibrium Conditions in the Presence of a Flue Gas 

Containing 15 Per Cent Carbon Dioxide. 

r h % K as % K as 

. L. k KHCO, 



10 0.369* 8.5 91.5 

20 .300* 9.5 90.5 

30 239' 11.6 88.4 

40 .182 14.2 85.8 

50 .132 18.0 82.0 

60 .096 22.2 77.8 

70 .068 27.3 72.7 

80 .045 34.0 66.0 

90 .031 40.3 59.7 

100 .020* 47.9 52.1 

110 .011* 57.6 42.4 

* Mechanically extrapolated. 

which was calculated by means of equation 48. The calculations were based 
on a 2N lye solution (about 12% K 2 CO 3 ) in equilibrium with a flue gas 
with a partial pressure of carbon dioxide corresponding to a 15 per cent 
carbon dioxide mixture. 

Some rather interesting points are brought out by this table. First it 
is evident that the lower the temperature the greater will be the bicarbonate 
concentration and that with 15 per cent carbon dioxide in the gas phase 
the bicarbonate in the liquid cannot be reduced below 40 per cent even at 
temperatures near the boiling point. This condition must not be confused 
with the process of boiling a bicarbonate solution, as in this case the par- 

TABLE 66. Showing the Relation Betivccn the Volume Per Cent 

of Carbon Dioxide and the Concentrations of Carbonate and 

Bicarbonate of Potassium at 30 C. in a solution 2 Normal 

With Respect to the Potassium. 

%KasKHCO, 

20 9.5 90.5 

18 10.0 90.0 

16 10.9 89.1 

14 12.0 88.0 

12 13.7 86.3 

10 15.7 84.3 

8 18.4 81.6 

6 22.3 77.7 

4 28.3 71.7 

2 39.9 60.1 

1 51.6 48.4 

0.50 62.5 37.5 

0.05 86.1 13.9 

tial pressure of carbon dioxide is decreased to a low value by the admix- 
ture of a very large volume of steam. It would seem from this table that 
the most efficient temperature for operating a coke tower would be about 



MANUFACTURE OF LIQUID CARBON DIOXIDE 157 

10 C. or less. While this would increase slightly the per cent of bicar- 
bonate in the lye over that usually obtained at the operating temperature 
of about 30 to 40 C. the question of heat economy and rate of absorp- 
tion makes a higher temperature more desirable. 

In order to show the influence of carbon dioxide concentration in the 
gas above a lye solution, on the concentrations of carbonate and bicar- 
bonate, Table 66 has been constructed from values calculated from the 
experimental results of Sicverts and Fritzsche. 

/Rate of Absorption. To a plant manager, the problem connected 
with the daily operation of the absorbing unit is simply one of keeping the 
available equipment continuously at the peak of its capacity. The fore- 
going discussion may help one to understand why certain conditions are 
necessary to get the maximum yield from an absorbing apparatus, but much 
more information is needed to aid one in designing and constructing a 
device for carrying it out. Plant capacities are usually rated on the pounds 
of carbon dioxide compressed into cylinders per hour. This is, of course, 
entirely dependent upon the absorption process because it is only that car- 
bon dioxide removed from the flue gas that ever gets into the cylinders. 
The many factors which influence this rate of absorption seem worthy of 
as complete discussion as we may give them with our present knowledge 
of the subject. 

Absorption Mechanism. Consider first, a solution of potassium car- 
bonate and potassium bicarlxmatc, and over this liquid, a gas composed of 
carbon dioxide, carbon monoxide, oxygen and nitrogen. While the carbon 
monoxide, oxygen and nitrogen are soluble to some extent in this solution, 
this solubility is so small compared to carbon dioxide that they will be 
considered as inert gases as far as this discussion is concerned. If both 
the liquid and the gas remain undisturbed, the carbon dioxide in the gas 
phase for a short distance from the liquid-gas interface will dissolve, leav- 
ing a layer of inert gas molecules through which all of the catbon dioxide 
from the main body of gas must pass before going into the alkali solution. 
While in the gas phase the carbon dioxide molecules may move from point to 
point by either convection or diffusion, through this film of inert molecules 
they can move only by the relatively slow process of diffusion. On reaching 
the surface of the liquid the carbon dioxide molecules must again pass 
through a film of inert material which in this case is composed of the ions 
and molecules of water, carbonic acid, etc. after which they can move into 
the body of the liquid by either diffusion or convection. This layer of gas 
molecules at the interface, composed chiefly of the slightly soluble gases, 
will be spoken of as the gas film while the layer of unreactive molecules 
at the surface of the liquid will be called the liquid film. 13 Due to the slow- 
ness of the process of diffusion the amount of gas absorbed in an unagitated 
system in a unit of time must be comparatively small because of the thick- 

ls Whitman, W. G., Chem. Met. Eng., 29, 147 (1923). 



158 CARKON DIOXIDE 

ness of the gas and liquid films under these conditions, but in an agitated 
system the surface of the liquid is greatly increased and the thickness of 
the films is decreased therefore the rate of material transfer is greatly 
accelerated. In a well-agitated system where the transfer of material can 
take place by convection in the body of the gas and in the body of the 
liquid the concentration of carbon dioxide in either is essentially the same 
at all points. On the other hand, the gas and liquid films being free from 
convection currents can transfer the carbon dioxide only by the relatively 
slow process of diffusion. These films therefore, act as a resistance to the 
transfer of carbon dioxide from the gas mixture to the lye solution and 
a study of the behavior of these films may throw some light on the question 
of rate of absorption. 

The driving force which causes the diffusion through the gas film is the 
difference in concentration of the gas F r ; on the outside of the film and its 
concentration on the inside Pi or at the interface. The rate of diffusion is 
therefore proportional to (PaPi). Diffusion of carbon dioxide through 
the liquid film is, in like manner brought about by the difference in con- 
centration of carbon dioxide at the interface d and in the main body of the 
liquid CL and the rate of diffusion will likewise be proportional to 
(Ci CL). It follows, therefore, that as long as all of the solute passing 
through the gas film must also pass through the liquid film the rates must 
be equal and that ka(P G Pi)=k Tj (Ci CL) where k and k L are dif- 
fusion coefficients for the gas and liquid films respectively. 

The amount of carbon dioxide W transferred per unit time 6 by dif- 
fusion through the two films is dW/dB and if S is the surface of the inter- 
face through which the diffusion is taking place then dW/dQS represents 
the diffusional current density. 14 

and dW/deS=k G (P -P i )^=k L (C i -C L ) ......... (49) 

It is possible to simplify this equation somewhat in cases where Henry's 
law holds by combining the two film coefficients into one overall coefficient 
KQ or K L . Then the equation may be written 



K G (P ( j-P L ) ........ . . . . (50) 

or dW/doS=K L (C G -C L ) ............ (51) 

In calculations involving this overall coefficient, of course comparable units 
must be used in both the liquid and gas phases although the choice of units 
is purely arbitrary. In liquid-gas solutions, in cases where Henry's law 
holds, the concentration of the gas in the liquid is determined by the par- 
tial pressure of the gas above the liquid. When the solvent contains some 
other compound with which the solute combines, the situation is somewhat 
different. Then the equilibrium conditions depend upon the dissociation 

14 Walker, Lewis and McAdams, "Principles of Chemical Engineering," page 653. McGraw- 
Hill Book Co., New York (1917). 



MANUFACTURE OF LIQUID CARBON DIOXIDE 



159 



pressure of the compound in question, the amount of gas dissolved as such 
in the liquid and the partial pressure of the gas above the liquid. A solu- 
tion of alkali carbonate in equilibrium with carbon dioxide gas is a system 
of this general type. These equilibrium conditions are very clearly shown 
in Figure 32. These curves were made by plotting the per cent of potas- 
sium existing as bicarbonate in a 2N solution of potassium carbonate 
against the partial pressure of carbon dioxide in equilibrium with the solu- 
tion, the partial pressures expressed in atmospheres. The data on which 
these curves are based were taken from Table 67 and are for a working 
temperature of 30 C. 




10 30 40 50 O 70 80 

Percent KHGOjin !/ sol and gms available CO, pr liter !>. 

FIGURE 32. Equilibrium Conditions in the System 
CO 2 -K 2 CO 3 -KHCO : ,~H 2 O. 

The driving potentials which cause the carbon dioxide to diffuse through 
the gas and liquid films can be determineu very quickly from these plots. 
Thus with a 60% KHCO lye solution the driving force, from a flue gas 
containing 18% COo would be 16, but if the concentration of the lye 
becomes 90% then the driving force becomes zero. The speed with which 
the carbon dioxide diffuses into the solution of potassium carbonate is pro- 
portional to this driving force and later, use of it will be made for such 
calculations. 

Experimental Verification. A study of the rates of absorption of 
carbon dioxide in potash or soda lye solutions has been made by Sieverts 



160 



CARBON DIOXIDE 



and Fritzsche, 15 Riou, 16 Williamson and Mathews, 17 and by Whitman and 
Davis, 18 and in general their results confirm this theoretical treatment. 

Figure 33 shows a number of curves representing the results obtained 
by Sieverts and Fritzsche on the rate of absorption of carbon dioxide from 
a gas mixture by means of a potash lye solution. Except for one curve, 
which is indicated, all of the data were obtained with solutions agitated at 
a constant rate. It is interesting to note that curve 1 a (without stirring) 
shows that the rate of absorption is a linear function of the time, as far 
as it is indicated, and that all other curves are nearly so up to the point 




2 3 

TfiM in Hour* 

FIGURE 33. The Rate of Absorption of Carbon Dioxide in Solutions 
of Potassium Carbonate. Experimental work of Sieverts and Fritzsche. 

where the rate falls off rapidly due to the high concentration of bicarbonate 
in the solution. The effect of agitation on the rate of solution is very pro- 
nounced, as one would expect. It will be noted that this rate is somewhat 
higher for the more dilute solutions, curves 4, 5 and 6, than for those of 
a higher alkali concentration curves 1, 2 and 3. This effect has also been 
observed by other investigators. Perhaps the most noteworthy thing, how- 
ever, is the apparent decrease in rate of absorption at higher temperatures 
as is indicated by both sets of curves. This change of rate with temperature 
does not agree with the results obtained by Williamson and Mathews who 
found that the rate increased up to 70 to 75 C. and then decreased ; and 

u Sieverts, A., and Fritzsche, A., Z. anorff. allgem. Chem., 133, 17-25 (1924). 
16 Riou, P., Compt. rend., 174, 1017-9 (1922). 

"Williamson, R. V., and Mathews,. J. H., Ind. Eng. Chem., 16, 1157-61 (1924). 
Whitman, W. G., and Davis, G. H. B., Ind. Eng. Chem., 18, 264-6 (1926). 



MANUFACTURE OF LIQUID CARBON DIOXIDE 161 

Whitman and Davis who found that the absorption rate coefficient in a 
bubble-plate tower doubled for every 24 C. increase in temperature. The 
conditions under which these various investigations were made, however, 
were quite different and this fact may account for the discrepancy. 

Other Factors Affecting the Rate or Degree of Absorption. In thef 
process of absorbing carbon dioxide in an alkaline solution the concentra- 
tion and purity of the lye solution used is of considerable importance. It 
is not uncommon for a plant executive to find it necessary to discard the 
lye solution and start over with a fresh one because of the building up of 
impurities within it. The expense involved in such a step is great, of 
course, especially so when potash lye is being used. It would seem there- 
fore, that it is quite desirable to investigate as fully as possible what effect 
the admixture of various substances has on the degree and the rate of 
absorption. 

Riou and Cartier 19 studied the effect of various concentrations of 
glycerol, dextrose and sucrose on the rate of absorption of carbon dioxide 
in solutions of sodium carbonate. This was done primarily to test the effect 
of viscosity, of the absorbing liquid, on the rate of solution. It was found, 
however, that all three compounds in low concentrations, increased the rate 
of absorption. It also appeared from the first set of experiments that the 
viscosity of the absorbing liquid had but little to do with the rate of absorp- 
tion. On the addition of 0.029 to 0.044 mole of sucrose per liter of solu- 
tion the rate of absorption was more than doubled. The addition of 0.056 
mole of dextrose also more than doubled the rate of absorption while the 
addition of glycerol up to concentrations of 0.43 mole affected the absorp- 
tion but slightly. 

In a later work Riou and Cartier 20 extended their investigation to 
include ethylcne glycol, levulose, methyl alcohol, ethyl alcohol, formalde- 
hyde and lactose. From the results of these investigations as well as of 
the previous ones they arrived at the following conclusions: (1) While 
the viscosity of the absorbing solution has some effect on the rate of absorp- 
tion of a gas by a liquid, it is in no case the principal factor involved. 
(2) The chemical function of the added organic crystalloid plays a very 
important, if not the preponderant role in influencing the rate of absorp- 
tion. (3) Organic crystalloids, not producing combinations with sodium 
carbonate, increase the rate of absorption even though they increase the vis- 
cosity. These investigators suggest that these rather surprising results 
might be produced by catalytic action and that they might lead to industrial 
applications. 

In 1929 Riou and Lortie 21 experimented on solutions of sodium car- 
bonate containing colloids. Peptone, pepsin, gelatin and starch were used 
for the colloidal substances and they found that the velocity of absorption 
was decreased on the addition of these colloids up to \ per cent concentra- 

"Riou, P., and Cartier, P., Comfit, rend., 184, 325-6 (1927). 
*Riou, P., and Cartier, P., Comfit, rend., 186, 1727-9 (1928). 
Riou, P., and Lortie, L., Compf. rend. f 186, 1543-6 (1929). 



162 CARBON DIOXIDE 

tion after which they no longer affected the rate of solution. The new 
velocity was about two-thirds that of the initial one. 

The effect that sulfating of a lye solution has on the rate of absorption 
of carbon dioxide has, unfortunately, never received the attention of 
research workers that it deserves. From a practical point of view this is a 
very important problem. Even with the most efficient scrubbing system 
known for the removal of sulfur dioxide from a flue gas, there is a slight 
but continuous addition of this compound to the lye solution. The result- 
ing sulfite ions in the presence of the free oxygen in the flue gas, soon 
become oxidized to sulfate ions. The net result is the loss of carbonate ions 
with a corresponding decrease in absorbing power. 

There are several disadvantages connected with the sulfating of a lye 
solution, the most important of which is the loss of active carbonate which 
will, of course, decrease the absorption rate. In addition the slight solu- 
bility of potassium or sodium sulfate at low temperatures often cause crys- 
tals to separate on cold nights thus endangering the pump impellers and 
stopping liquid lines. Whether there is any negative effect on absorption 
rates due to the sulfate ion, has in the past never been definitely known 
although some operators believe that such an effect is present. The theory 
of absorption just discussed, however, points to the probability that sulfate 
ions would actually decrease the rate of solution. It is well known that 
the presence of sodium sulfate in water decreases very greatly its absorp- 
tion capacity for carbon dioxide. Thus the absorption coefficient for car- 
bon dioxide in pure water at 15 C. is 1.019 but in a 2 molar solution of 
sodium sulfate at the same temperature it is only 0.234 while a 2 normal 
solution of potassium sulfate has an absorption coefficient of 0.676 at 
15.5 C. This being the case, reference to the equilibrium equation shows 
at once that the carbon dioxide concentration at equilibrium would be 
decreased and therefore the rate of absorption would be decreased also. 
Then again, any foreign material in the solution would tend to increase 
the liquid film thickness thus setting up a greater resistance to the pas- 
sage of carbon dioxide through it with a resulting decrease in the rate of 
absorption. The experiments of Riou and Lortie with colloids confirm this 
view of the situation but the behavior of crystalloids such as sugar, etc. 
do not substantiate it. A recent unpublished research conducted by Clark 
and Austin 22 seems to indicate that the addition of potassium sulfate or 
sodium sulfate to the corresponding alkaline carbonate solution does not 
decrease the rate of absorption even when such substances are added to the 
saturation point. The work of these investigators is, perhaps, of sufficient 
importance to justify a more detailed description here. 

The experiments of Clark and Austin were carried out on a miniature 
carbon dioxide plant which is represented diagrammatically in Figure 34. 
An artificial flue gas, made from air and pure carbon dioxide, was sent 
through an absorption tower counter-current to the absorbing liquid. 
Absorption experiments were made on solutions of sodium carbonate and 

"Clark, W., and Austin, R., Dissertation, University of Utah (1932). 



MANUFACTURE OF LIQUID CARBON DIOXIDE 



163 



potassium carbonate and various mixtures of these with other compounds. 
It was possible to control the purity and concentration of these absorbents 
very accurately. The capacity of this carbon dioxide plant varied with the 
operating conditions up to 6 or 8 cu. ft. of carbon dioxide per hour. Pure 
carbon dioxide liberated from the lye boiler was collected in a standard 
gasometer and its volume carefully determined. The ingoing carbon diox- 
ide used for making the artificial flue gas was measured with a calibrated 
recording meter and the volume thus obtained was used with the readings 
of the standard gasometer for calculating the absorption efficiency for each 
run. The absorption efficiency was the ratio of carbon dioxide recovered 
to that entering the system. The absorption tower was packed with steel 




FIGURE 34. Experimental Carbon Dioxide Plant of Clark and Austin. 

borings and had an absorbing capacity so great that in some cases the con- 
centration of the lye solution had to be decreased considerably in order to 
bring the absorption down into a region where comparisons between runs 
could be made. 

A series of experiments with a 1.44 N potassium carbonate solution 
gave an average absorption efficiency of 75.7 per cent. When potassium 
sulfate was added sufficient to make a 5 per cent solution, the absorption 
efficiency was 77.9 per cent, whereas a saturated solution of the sulfate 
gave 78.7 per cent efficiency. The probable error of these measurements 
is somewhat difficult to estimate but without doubt it is not greater than 
two or three per cent. 

Clark and Austin also attempted to determine the action of dextrose on 
the absorption efficiency of potassium carbonate solutions. It will be 
recalled that a commercial application of a dextrose-alkali carbonate solu- 



164 CARBON DIOXIDE 

tion had already been suggested. A series of runs gave the average absorp- 
tion efficiency of a 2 N solution of potassium carbonate as 70.8 per cent, 
5 per cent dextrose raised this to 94.2 per cent and 10 per cent dextrose 
increased it again to 104.9 per cent. Only two runs were made on this 
more concentrated dextrose solution but both of them showed a yield bet- 
ter than 100 per cent. The gas had a very disagreeable odor and showed 
only 99.3 per cent carbon dioxide. It is very probable that only one 
definite conclusion can be drawn from these results, and that is, while 
the dextrose does increase the absorption as has been reported there is 
absolutely no commercial possibility of its use because of the odor it imparts 
to the gas. 

The experiments these authors conducted with sodium and potassium 
carbonate solutions, to which had been added triethanolamine, arc excep- 
tionally interesting. A 0.5 N potassium carbonate solution showed an 
absorption efficiency of 54.9 per cent, 1 per cent triethanolamine increased 
it to 73.6 per cent and 2 per cent triethanolamine raised it again to 76.0 
per cent. When a 0.5 N solution of NaoCO 3 was used it showed an absorp- 
tion efficiency of 43.8 per cent, 1 per cent triethanolamine raised it to 54.9 
per cent and 2 per cent triethanolamine gave 55.0 per cent. The gas pro- 
duced by this absorbing agent seemed to be free from objectionable odors 
and as far as one could tell from a superficial examination no appreciable 
decomposition of the triethanolamine took place. 

The Coke Tower. The coke tower is a vertical tube of sheet steel 
with connections for gas intake and liquid exit at the bottom and gas exit 
and liquid intake at the top. Figure 35 shows in section the conventional 
design of such absorption towers together with the lye tanks and pipe 
connections. It is necessary to have several supporting platforms spaced 
from 10 to 15 feet apart within the tower to support the load of coke or 
other packing in it, thus relieving the packing at the bottom of the tower 
from the weight of that above. Another important structural detail is the 
method of spreading the lye over the top of the coke. Unless this is well 
done there is apt to be a large amount of coke unwet with the resulting 
loss in absorbing capacity. A simple and effective spreader can be made 
by running a main feed pipe across the top of the tower in a plane at right 
angles to the tower, a number of lateral pipes are connected with this feed 
line and extend to the edge of the tower. These lateral pipes are capped 
at the ends, as is also the open end of the main feed line. A calculated 
number of holes are drilled in the top side of all these pipes so the lye is 
forced up through them in the form of small fountains. With this arrange- 
ment the spreading of the lye is uniform over the top of the coke regard- 
less of the variations in the rate of flow. 

Two coke towers are often connected in series and arranged so that 
the exit gas from the first passes to the bottom of the second and the exit 
liquid from the second passes to the top of the first. In some cases a coke 
tower is used for washing the flue gas with the stronger lye solution after 
which the gas stream is divided and sent to two finishing towers for the 



MANUFACTURE OF LIQUID CARBON DIOXIDE 



165 



filial treatment with a weak lye solution. Two towers 10 feet in diameter 
by 100 feet high, connected in series will absorb about 1000 pounds of car- 
bon dioxide per hour from a high grade flue gas if the rest of the plant is 
properly designed. 

Other Types of Absorbers. Iron borings and turnings are being 
used in some plants for absorber packing. The surface exposed by this 
type of filling material is very much greater than that exposed by coke 
and therefore a much greater absorption efficiency is obtained. The initial 
cost of filling such towers is much greater than in the case of coke packing. 



Flu. Go. EMI* . 



FIGURE 35. 

Arrangement of Lye Tanks 
and Coke Absorption Towers. 




The difficulty of cleaning oil from the iron before packing the tower is very 
great and an item of no small expense. This is accomplished by boiling 
the iron in sodium carbonate solution and then washing with water but 
even then traces of oil get into the system causing considerable trouble. 
How this type of packing will stand up with continual use is not known 
at present. Certain recent developments seem to indicate that this tower 
packing is not as successful as was hoped for at first. Reports are current 
that certain plants have removed this packing from the absorbers and 
refilled them with coke. The exact reason for this change is, however, not 
generally known. 

Experiments with bubble-plate towers indicate a very high absorption 
efficiency. This is to be expected because of the rapidly changing liquid 
film as the bubbles of gas pass through the absorbing liquid. Such an 
absorber is expensive and requires a flue gas under several pounds pres- 



166 



CARBON DIOXIDE 



sure. Table 67 from Goosmann 23 shows the relative efficiencies of the 
coke-packed tower and the bubble-plate tower. 

TABLE 07. Comparison of A bsorption Efficiencies of 
Coke-packed Towers and Bubble-plate Towers 





Sodium carbonate solution 


CO 2 in 
flue gas 


Exit gas % 


Conversion % 


Gals, per mm. 


Coke per hr. 


% 


Coke 


Bubble 


Coke 


Bubble 


Coke 


Bubble 


Coke 


Bubble 




Tower 


Tower 


Tower 


Tower 


Tower 


Tower 


Tower 


Tower 


16 


9.0 


6.5 


60-30 


70-30 


786 


590 


3,540 


2,640 


14 


8.5 


6.3 


58-30 


6S-30 


848 


615 


3,950 


2,820 


12 


8.0 


6.1 


54-30 


66-30 


986 


654 


4,650 


3,150 


10 


7.6 


5.9 


50-30 


64-30 


1,180 


700 


6,460 


3,790 



Potassium carbonate solution 



16 


No coke 


4.5 


No coke 


70-30 


No coke 


243 


No coke 


2,160 


14 


tower 


4.3 


tower 


68-30 


tower 


256 


tower 


2,240 


12 


used 


4.2 


used 


66-30 


used 


270 


used 


2,385 


10 




4.1 




64-30 




283 




2,630 



The soda solution contained 6.14 Ibs. of Na.CO a per cu. ft. and the potash solution con- 
tained 19.5 Ibs. KjfCOj per cu. ft. 

The Operation of a Coke Tower. Drane 24 summarizes the factors 
affecting the operation of a gas scrubbing tower as follows : 

(a) Solubility relationships of gas and scrubbing liquid. 

(b) Special considerations : (1) Temperature changes, (2) formation 

of compounds, (3) viscosity. 

(c) Rates of liquid and gas flow. 

(d) Scrubbing surface, nature and extent. 

The solubility relationships of gas and scrubbing liquid have already 
been considered, as well as such special considerations as temperature, for- 
mation of compounds, viscosity, etc. Attention will now be directed to the 
effect of rates of liquid and gas flow. 

When a change is made in the rate at which an absorbing liquid is 
pumped over the packing in a coke tower there are several variables which 
may affect the rate of absorption. First, the area of wet surface may be 
increased or decreased resulting in an increased or retarded rate of absorp- 
tion. These changes in rate of absorption will, of course, be proportional 
to the change in the active surface. Increasing the rate of liquid flow 
beyond the point where all of the coke is wetted will, by its turbulence, 
increase the surface of lye and therefore the rate of absorption. The extent 

a3 Goosman, J. C. t Ice and Refrigeration, 79, 399 (1930). 
"Drane. H. D. II., /. Soc. Chem. Ind. t 43, 329-34 T (1924). 



MANUFACTURE OF LIQUID CARBON DIOXIDE 167 

of this increase depends largely upon the nature of the tower packing and 
the quantity of liquid passing over it. Williamson and Mathews 25 investi- 
gated this effect for three, different types of absorbers : ( 1 ) a baffled tower ; 
(2) the same tower packed with approximately round pebbles 2.5 cm. in 
diameter; (3) a specially constructed absorption box in which the surface 
of the liquid was nearly level and without movement in any particular 
direction, although the liquid beneath the surface was flowing at the rate 
of 10 cm. per second. 

By increasing the rate of liquid flow by 100 per cent after the surface 
over which the solution flowed was completely wet, the following increases 
in rate of absorption were observed : 

Pebble-packed tower 66 per cent 

Baffled tower SO per cent 

Special absorption box 25 per cent 

These values seem to indicate that the increase in rates were due largely 
to the surface increase as it was more pronounced in cases where the 
greater turbulence resulted. 

In most plants the rate of flow of flue gas is not subject to control. It 
depends on the rate of combustion, and the rate of combustion is determined 
by the steam consumption or in some cases by the quantity of lye boiled. 
An increase in the rate of gas flow will increase the rate of absorption 
because of the higher average carbon dioxide content of the gas within the 
tower and the decrease of the gas film due to the turbulence of gas flow. Yet 
the carbon dioxide lost to the atmosphere will become greater because of the 
larger quantity of it that escapes in the exit gases. Williamson and 
Mathews found that an increase of 100 per cent in the rate of gas flow, 
when a slight excess of carbon dioxide was passing through the tower, 
caused an increase of 40 per cent in the rate of absorption and a loss of 
slightly over 60 per cent of the increased flow of carbon dioxide. This 
means that the percentage loss was multiplied many times by doubling the 
rate of gas flow over that which produced a slight excess in the tower. 
The application of this data to coke tower design is quite clear. For the 
maximum efficiency, that is ratio of gas recovered to that produced, a flow 
rate for gas should be as low as is consistent with the cost of the tower. 
This low rate may be obtained by increasing the diameter of the absorber. 
+S Lye Boiling. The liberation of carbon dioxide, taken up by the lye 
stream during its passage through the absorber, is accomplished by boiling. 
This operation is essentially the reverse of the absorption process. While 
it has been stated that the absorber is a very important part of the carbon 
dioxide plant it must also be emphasized that the lye boiler is no less 
important. The equipment used for removing carbon dioxide from the 
strong lye may vary from a very simple fire-tube steam boiler to an elab- 
orate and carefully engineered lye boiler designed for the most economical 
heat utilization. 

"Williamson, R. V., and Mathews, J. H., Ind. Eng. Chern., 16, 1157-61 (1924). 



168 



CARBON DIOXIDE 



Most plants are designed so that not more than 20 to 25 per cent of 
the lye flowing through the coke tower is diverted through the lye hoiler. 
Thus the absorbing lye passes through the absorber about 4 to 5 times for 
each passage through the desorber. As the amount of carbon dioxide 
transferred in each case is exactly the same the two units must be designed 
so they will have the same working capacity. 

Figure 36 shows a sectional drawing of an old-type vertical, steam- 
heated lye boiler. The rated capacity of this boiler with dimensions as 



5 Steam Inltt 




A" Go. Outlet 



^Ly L*I 
* 4* Lye Ou 



Lye Outlet 




Strong Ly 



Gonderued Steam 



I* Onp 

FIGURE 36. FIGURE 37. 

Vertical Lye Boiler. Modern Vertical Lye Hoiler. 

6 feet in diameter. 
50 feet high. 
15 bubble plates. 

Capacity 2000 Ibs. Carbon Dioxide 
per Hour. 

indicated, is about 250 pounds of carbon dioxide per hour provided the 
lye flow is about 50 gallons per minute and the heating surface is not less 
than 300 square feet. Figure 37 shows a diagram of a modern, steam- 
heated vertical lye boiler. This boiler, 6 feet in diameter, 50 feet high and 
with a tubular heating area of about 1300 square feet is capable of pro- 
ducing approximately 2000 pounds of carbon dioxide per hour. The rec- 
tification is accomplished by means of fifteen bubble plates arranged above 



MANUFACTURE OF LIQUID CARBON DIOXIDE 



169 



the boiler. Rectification in a case of this kind is very simple as the bubble 
plates act more like heat exchangers or steam condensers. The hot strong 
lye is fed to the top plate direct from the lye heat exchanger and at a 
temperature not far below the boiling point. The heat picked up in the 
lye heat exchanger comes from the hot lye discharged from the bottom 
of the lye boiler. The carbon dioxide is discharged from the top plate 
chamber of this lye boiler under a pressure of about 20 pounds per square 
inch. 

The horizontal lye boiler requires more floor space but it has certain 
advantages which make up for this to a certain extent. Figure 38 shows 
in section the details of a "Carbondale" lye boiler and its rectifier. This 
boiler is heated by exhaust steam obtained from the pumps and engines in 
the plant ; a small amount of live steam may also be necessary. As in the 
case of all steam-heated lye boilers the condensed steam is returned as feed 
water to the steam boiler. The rectifier on this lye boiler is essentially a 



Strong Lyt Inlet 




Exhaust Steam Inlet 



' 1 ^ 7ET 

FIGURE 38. Carbondalc Lye Boiler. 

bubble-plate column but it lacks the efficiency obtainable with the more 
carefully designed bubble-caps in the vertical boiler just described. While 
boiling, the lye moves slowly from one end of the boiler to the other and 
is finally discharged through the weak lye outlet. The boiler is capable 
of very exact control of lye flow and boiling rate. 

Many lye boilers are fitted with a constant level float valve so arranged 
that when the level of the lye falls a little, more steam is admitted to the 
strong lye pump which, in turn, speeds up and increases the flow of lye 
into the boiler. In this way the level is kept constant and smooth boiling 
results which relieves the operator of much care and trouble. The tem- 
perature of the solution and therefore its rate of boiling, can be kept prac- 
tically constant regardless of changes in the rate of lye flow, by one of 
the many excellent temperature regulators now on the market. The ther- 
mometer of this regulator is usually placed in the weak lye exit pipe and 
the control mechanism connected with the live steam inlet to the heating 



170 CARBON DIOXIDE 

coils. When the temperature of the lye falls this device opens the valve 
slightly on the live steam line and permits more steam to enter the boiler 
which quickly brings the temperature up to the desired value. 

Theory of Desorption or Lye Boiling. Perhaps it will not be out of 
place at this point to add a short discussion of the theory involved in thel 
separation of carbon dioxide from lye solutions. For this purpose data 
obtained on potassium carbonate solutions are more modern and complete 
and this discussion can be based on this data to an advantage. The ques- 
tion of how closely commercial systems approach equilibrium conditions is 
always difficult to estimate and therefore a theoretical discussion is apt to 
deviate considerably in some cases from industrial experience. 

By means of the equation 

2f*N 



and a value of 0.02 for k obtained by extrapolating the data of Sieverts and 
Fritzsche to 100 C. one can calculate the partial pressure of carbon diox- 
ide in equilibrium with solutions containing various percentages of bicar- 
bonate of potassium at the boiling temperature of the solution. The other 
component of the gas phase being steam makes it a simple matter to cal- 
culate the weight of carbon dioxide per pound of steam coming from the 
lye boiler at different percentages of bicarbonate in the solution. Table 68 

TABLE 68. Composition of Gas and Liquid Phases Obtained in Lye Boiling 

t=100, k=0.02. 

Per cent Lbs. CO a . co Per cent CO a Per cent H 8 O Lbs. CO a 

bicarbo- per ^* .*ir. in gas in gas per 

nate Ib.oflye mm.ofHg mixture mixture lb.H 2 O 

80 0.0316 640 84.2 15.8 13.02 

75 .0295 450 59.2 40.8 3.55 

70 .0277 326 41.5 58.5 1.73 

60 .0237 180 23.6 76.4 .755 

50 .0198 100 13.1 86.9 .368 

40 .0158 53 6.9 931 .181 

30 .0118 26 3.4 96.6 .086 

20 .0079 10 1.3 98.7 .032 

10 .0039 2 .3 99.7 .007 

shows the results of such calculations and Figure 39 shows the equilibrium 
curve obtained by plotting the weights of carbon dioxide per pound of 
steam in the gas phase against the per cent bicarbonate in the liquid phase. 
The most striking thing about this curve is the very rapid increase in the 
partial pressure of carbon dioxide in the gas phase at concentrations of 
bicarbonate above 70 per cent and the very slight increase at concentra- 
tions below 50 per cent bicarbonate. If one could produce, by absorption 
in a coke tower, a lye containing 80 to 85 per cent bicarbonate the process 
of lye boiling would indeed be a very simple one. The solution would 
hardly require boiling as the carbon dioxide would be evolved copiously at 
temperatures near the boiling point. On the other hand solutions con- 



MANUFACTURE OF LIQUID CARBON DIOXIDE 



171 



taining less than 40 or 50 per cent bicarbonate would require a great deal 
of boiling to obtain an appreciable yield of carbon dioxide. As the attain- 
ment of high bicarbonate concentrations seems to be impossible with the 
present method of absorption the working range is limited to the section 
between about 50 and 75 per cent bicarbonate. 

The curve in Figure 39 shows at a glance why the concentration of 
bicarbonate in a lye solution is not decreased in a commercial plant to a 
lower value. The cost of separating the carbon dioxide from the alkaline 



20 30 

P*r Cnt 



40 50 60 70 

K in form of Bicarbonate 



80 



90 



FIGURR 39. Curve Shows Carbon Dioxide in Equilibrium 
with Potassium Bicarbonate Solution at its Boiling Temperature. 

solution increases very rapidly as bicarbonate concentration decreases and 
a point is soon reached where continued boiling of the solution is no longer 
economical. 

Condensers. The particular type of condenser used for condensing 
the steam from the gaseous carbon dioxide is of no great importance as 
long as the condensation equipment is sufficient to meet the plant needs. 
Surface condensers consisting of a simple coil of pipe over which the cool- 
ing water is flowed have some advantage because of the ease of cleaning. 
Inclosed tubular condensers, however, are more economical in water con- 
sumption. A surge tank or a condenser sufficiently large to serve this pur- 
pose is desirable to take care of the hot lye which at times is apt to froth 
over from the boiler. This tank is, of course, connected to the lye tank 
through a trap so any lye collected in it will be returned to the absorption 
system. A trap is also connected to the condensing system to separate the 
condensed water from the carbon dioxide and returning the former to the 
lye solution. 



172 



CARBON DIOXIDE 



Gasometer. In some plants a small gasometer is placed in the car- 
bon dioxide line to smooth out the inequalities in the rates of production 
and compression. This can be used to an advantage only where the lye 
boiler operates under a pressure near atmospheric. Many plants, however, 
operate the lye boiler so as to furnish gas to the suction port of the com- 
pressor at a pressure of about 20 pounds per square inch. In such cases 
the operation of the lye boiler and compressor is So conducted that a gasom- 
eter is unnecessary. 




Courtesy, Safety Mining Company. 

FIGURE 40. Showing End View of Carbon Dioxide Compressor, 
Solution Pumps in the Foreground, Silica Gel Dryer and Potassium 
Permanganate Scrubber in the Left Background. 

Purification^ The carbon dioxide at this point besides being satu- 
rated with water vapor often contains a faint but undesirable foreign odor. 
The cause of this odor is unknown but it is generally supposed to be due 
to oxidizable organic bodies carried from the raw flue gas by the carbon 
dioxide. Chemical treatment for the removal of these odors is often 
resorted to in which case the gas is scrubbed with a solution of potassium 
permanganate. Such a chemical purifier is shown in Figure 40. 

The first step in the process of dehydration of the carbon dioxide is to 
lower its temperature, by means of a simple cooler, to that of the water 
supply. Assuming a gas saturated with water at 25 C. and a cooling 
water of 12 C. the cooling operation will then change the water content 
from 0.01304 pounds per pound of carbon dioxide to 0.00569 pounds of 
water per pound of carbon dioxide. The difference between these two 



MANUFACTURE OF LIQUID CARBON DIOXIDE 



173 



values represents the water separated by condensation. Such a cooler soon 
pays for itself by removing much of the load from other dehydrating units. 

The final dehydration operation may be conducted with a calcium chlor- 
ide tower, by means of refrigeration, by adsorption of^ater on silica or 
alumina gel, or by a combination of these methods. ^/ 

The calcium chloride tower is the most important chemical dehydrator. 
Such an apparatus will dry a carbon dioxide gas stream very effectually 
when it is kept in the proper working condition. These dryers require 
considerable attention, however, and the authors have seen some in such 
a state of neglect that they served no purpose whatever. As a matter of fact 
some plants make no effort to dry the gas beyond the point reached with 
a good gas cooler. 

Dehydration by means of refrigeration is not a new process nor is it 
confined to carbon dioxide gas alone. The cooling may be produced by 
means of a separate refrigeration unit or by simply expanding some of the 
liquid carbon dioxide back into the suction gas stream. One type of dehy- 
drator found by the authors in a liquid plant is quite interesting and a 



FIGURE 41. 

Carbon Dioxide Dehydrator. 




Brin* Outlet 



drawing of it is given in Figure 41. The cooling of the salt brine in this 
dehydrator is effected by an auxiliary refrigeration machine. The carbon 
dioxide gas is passed through this brine and as the water content of the 
solution increases by the resulting condensation more solid salt is added 
and the excess brine is drawn off. This refrigerating unit or any other 
capable of reducing the temperature of the gas stream to 5 C. (23 F.) 



174 



CARBON DIOXIDE 



will decrease the water content to 0.0017 pound per pound of carbon 
dioxide. A recent development in the art of drying gases, with the aid of 
silica gel, is especially fitted to the carbon dioxide industry. This dehy- 
drating substance, which has a remarkable adsorptive capacity for water 
and other gaseous impurities, is being used more and more in the process of 




Courtesy, Safety Mining Company. 

FIGURE 42. Carbon Dioxide Compressor with a Capacity of 600 
pounds of Carbon Dioxide per Hour. Built by the York Ice Machine 
Company. 

carbon dioxide purification. .The adsorption process on which its drying 
properties depends is entirely a physical reaction and can be reversed by 
simply changing the temperature of the charge. 

The adsorbers, in which carbon dioxide is brought in contact with the 
enormous surface exposed by the silica gel, are simple tanks designed to 
withstand the working pressure of the gas. These tanks are usually 
arranged in duplicate so that while adsorption is taking place in one the 
other is undergoing reactivation. After the silica gel becomes saturated 
with water, the adsorber is cut out of the system and air at a temperature 
of 300 to 500 F. is passed through until all of the water is vaporized and 
removed from the adsorber. The unit is then ready to be cut into the system 
again at 100 per cent of its original effectiveness. The two adsorbers are 
usually placed close together with an air pump and air heater mounted on 
the same frame. Changing the flow of gas from one to the other is accom- 
plished by simply operating a valve. The adsorption cycle will vary from 



MANUFACTURE OF LIQUID CARBON DIOXIDE 175 

2 to 10 hours depending upon the rate of flow and the size of the adsorber. 
It is stated that the operating cost varies from 5 to 15 cents per ton of 
carbon dioxide treated. The purified carbon dioxide can be dried to a water 
content of 0.006 per cent by weight or even less. 

Silica gel adsorbers are designed for low pressures so they can be used 
on the suction line of the compressor. They are also designed for high 
pressures so they can be used between stages while the gas is being com- 
pressed. A favorite position is between the second and third stages on a 
threenrtage compressor. 

S/Liquef action of Carbon Dioxide. The final major operation in pre- 
paring carbon dioxide for the market is the process of compressing and 
condensing. (See Figure 42). Increasing the gas pressure to a- point 
where it is liquefied by the cooling effect of the condensers may be accom- 
plished by several types of machines. Compressors have been constructed 
with one, two, three and four stages but the latter two are the only ones 
important at the present time. One also finds both the vertical and the hori- 
zontal types of machines: Figure 43 shows a sectional view of a standard 
horizontal three-stage compressor. 

The problems connected with carbon dioxide liquefaction differ but 
slightly from those encountered in liquefying other gases. In this case, 




Courtesy, Norwalk Company, Inc. 

FIGURE 43. Sectional View of a Standard Carbon Dioxide Compressor. 

however, the liquefaction takes place at temperatures only a little below the 
critical point while most other liquefied gases used for commercial purposes 
have relatively high critical points. 

The proper lubrication of a carbon dioxide compressor has always been 
somewhat of a problem. Lubricating oils unless very highly refined impart 
to the carbon dioxide an undesirable odor which lowers the grade of the 
product. For this reason glycerol was largely used as a lubricant. Glycerol, 
however, is not an ideal lubricant. The fact that it is miscible with water 



176 



CARBON DIOXIDE 



in all proportions makes it liable to dilution in the cylinders of a compressor 
to a point where it has no lubricating properties. Furthermore high tem- 
peratures tend to decompose glycerol with the formation of acrolein a sub- 
stance having a very penetrating and disagreeable odor which would be 
needed in only a trace to make the carbon dioxide unmarketable. The 
general practice now, is to use a very highly refined mineral oil for com- 
pressor lubrication. Several types of oil, suitable for compressor lubrication, 
are available and in general they are odorless, tasteless and colorless. 

Oil Removal. ^The tendency for oil droplets to leave the compressor 
with the highly compressed carbon dioxide is sufficient to make an oil sepa- 
rator necessary. It is not possible to state definite upper limits below which 




Iron Win Screen* 



Rack With Asbestos 



I Steel 
Raschig Rings 
Scramble Packed 




id! 



- Asbestos Packing 



/,"$& pyvxTPvyl 
n /& 



FIGURE 44. Typical Oil Filters. 

oil must be reduced, because of the variety of conditions under which com- 
mercial liquid and solid carbon dioxide is used. Amounts in no way objec- 
tionable for industrial application of either liquid or solid, will meet instant 
rejection of the solid when applied to paper carry-home ice cream packages. 
The oil content of commercial products ranges from none at all when 
glycerol is used as a lubricant, to 0.02 per cent, although percentages as 
high as 0.03 are not objectionable in the shipping of most food products, 
packed with the solid, when colorless compressor oils are employed. 

Two types of oil traps are illustrated in Figure 44, and it is obvious 
that any construction suitable for high pressure gases, and embodying 
features of low gas velocity and change of direction, will serve the purpose. 

It is important, regardless of the mechanical detail of oil separation 
equipment, that oil separators should be operated above the critical temper- 
ature of carbon dioxide, since otherwise the liquid carbon dioxide will 
dissolve and flood out of the separator a portion of the oil. Also while 
lubricating oil will readily separate as a bottom layer with liquid carbon 
dioxide at temperatures above about 10 C. at lower temperatures the two 



MANUFACTURE OF LIQUID CARBON DIOXIDE 177 

layers change places thus making it possible for the oil to flow from the top 
of the trap into the liquid carbon dioxide system. 20 On the other hand, 
separation is more effective at low temperatures than at high ; hence, certain 
plants have made a practice of removing a portion of the superheat prior 
to oil separation, maintaining oil separators at temperatures from 100 to 
120 F. and this practice has much to commend it. 



^Liquid 



Carbon Dioxide Condensers. The only characteristic of 
importance in the condensers used for the liquefaction of the highly 
compressed carbon dioxide is that they be constructed to withstand the very 
high pressures to which they are subjected. Coils exposed to the atmos- 
phere, over which water is flowed, coils submerged in cooling water and 
the double-pipe condenser are perhaps the most popular types. Accessi- 
bility for repairs is often necessary because of the serious corrosion to which 
these condensers are sometimes subjected. In some cases, this corrosion is 
serious enough to make a renewal of the condenser necessary every few 
months. The cause of this was shown by Hackspill and Couder 27 to be 
due to the formation of 'nitrites from the combined nitrogen of the coke 
which is absorbed by the alkali carbonate solution to form potassium nitrite. 
On boiling the lye solution, containing small amounts of the nitrite, a small 
amount of HNO 2 is liberated (KNO 2 + HoCO 3 = KHCO 3 + HNO 2 ) which 
decomposes as follows: 3HNO 2 = H 2 O + HNO3 + 2NO. It is supposed 
that the corrosion is due to this nitric acid. 

>/ THE SURTH SYSTEM FOR MANUFACTURING CARBON DIOXIDE 

Some years ago, the Siirth Machine Works in Surth, Germany, intro- 
duced a radical departure in the coke process for manufacturing carbon 
doxide. 28 The principal difference between this and the common coke 
process was in the method of burning the coke and the process of absorbing 
the carbon dioxide from the combustion gases. The coke or coal was 
burned in a generator for the production of a high-grade producer gas. 
After purification the producer gas was burned in an internal combustion 
engine for the production of power and an exhaust gas rich in carbon 
dioxide. The exhaust gas from such a motor may contain from 18 to 18.8 
per cent carbon dioxide. 29 

The absorption of carbon dioxide from the motor exhaust gas was 
conducted under a pressure of from 4 to 5 atmospheres. Furthermore, the 
absorption took place at a temperature near the boiling point of the lye 
solution, thus making unnecessary the cooling of the lye stream after the 
expulsion of the carbon dioxide in the lye boiler. This made heat exchangers 
of little value and the heat saved in this way was expected to be a factor 
towards a high thermal efficiency in the process. However, the need of 



n, E. L., Ind. Enrj. Chctn. t 20, 735-40 (1928). 

Hackspill. I., and Couder, A., Comfit, rend., 176, 1811-13 (1923) ; Chimie et Industrie, Special 
No., 404-5 (May, 1924). 

88 D. R. P. 162,655 and 173,130 to E. A. Behrens and J. Behrens. 
Espenmialler, 7. komfir. flilss. Case, 25, 10 (1926). 



178 CARHON DIOXIDE 

compressors to raise the pressure of the exhaust gas to the required value 
added a power expense which offset this heat saving to a considerable 
extent. Then the expense of constructing an absorher sufficiently strong 
to withstand this high absorption pressure, together with the difficulties 
encountered in operation took away practically all advantage gained by 
the thermal efficiency. This process, to a certain extent, was an isothermal 
reaction in which the carbon dioxide formed bicarbonate of potassium 
because of its increased partial pressure in the flue gas stream and was 
again separated in the boiler by the reduction of this pressure. The 
yield of carbon dioxide per pound of coke in this process, was said to be 
from 1.3 to 2 pounds. 

The original Siirth process has been modified considerably in recent 
years. The generator gas plant as a source of cheap fuel has been retained 
but the pressure absorption system has been discarded. This modified 
process spoken of as the Linde-Siirth process has certain advantages over 
the common coke process, especially in places where a high-grade coke is 
expensive or difficult to obtain. 

Figure 45 shows in diagrammatic form the most important features 
of the Linde-Siirth process. The gas producer (1) consists of a universal 
closed shaft furnace on the grate of which a thick layer of fuel rests. Air 
drawn through this mass of heated fuel, by suction, produces a com- 
bustible gas consisting of carbon monoxide with perhaps a little hydrogen, 
formed by the water gas reaction from the moisture in the air used. 
Automatic charging devices may be used in the larger plants to keep the 
fuel level in the generator at the proper height. The gas stream from the 
producer is first purified in the wet scrubber (2) and then in the dry 
purifier (3). The part of the gas needed for operation of the lye boiler 
is removed from the dry purifier with a special Mower (4) while that 
used for power is drawn out by the suction of the gas engine (5). The 
exhaust gas from the engine is passed through the water scrubber (7) 
and then combined with the combustion gas from the lye boiler (6) after 
which the combined gases are washed in the water purifier (8) and the 
soda lye scrubber (9). The blower (10) then forces the purified flue gas 
up through the coke tower (11) counter-current to the stream of potassium 
carbonate which is sprayed over the coke packing. The bicarbonate solu- 
tion thus formed is then forced, by means of the lye pump (12) through 
the heat exchanger (13) and (14) to the dome of the lye boiler (6). In the 
dome of the lye boiler the incoming solution is preheated as it passes down 
over the Rauschig rings, used as packing for the dome, which are in turn 
heated by the mixture of steam and carbon dioxide coming' from the 
lye boiler. The spent lye coming from the lye boiler is returned to the 
absorption system, through the heat exchanger (14) (IS) where it gives 
up heat to the incoming strong lye. The exchanger (15) is water-cooled 
and gives to the lye the right temperature for maximum absorption rate. 
The lye pump (16) returns the weak lye to the top of the absorbing tower 



MANUFACTURE OP LIQUID CARBON DIOXIDE 



179 



where it goes through the cycle again. The carbon dioxide with some 
water vapor coming from the top of the lye boiler is first cooled in the 
exchanger (13), the water thus condensed is separated and sent back to 
the lye stream, while the gas is sent to the gas holder (17). In the purify- 
ing and compression system the gas is first dried with calcium chloride in 
the drier (18) and then sent through the carbon purifier (19). After the 




FIGURE 45. The Linde-Siirth Process for Manufacturing Carbon Dioxide. 

first stage of compression in the compressor (20) the gas is further dried 
in the tower (21). From the third stage of the compressor it passes 
through the oil separator (22) and to the condenser (23) and finally filled 
into the steel cylinders (24). v 

v' CARBON DFOXIDE FROM CARBONATES 

The liberation of carbon dioxide from calcium and magnesium car- 
bonates by means of acids was one of the first industrial methods of pre- 
paring commercial carbon dioxide. This process is still of some importance 
at least to a certain extent from an industrial point of view. Natural car- 
bonates found in tremendous quantities contain high percentages of carbon 



180 CARBON DIOXIDE 

dioxide, a large amount of which is readily recovered on a commercial 
scale. Thus limestone, marble, chalk, aragonite, calcite, etc., all more 
or less pure carbonates of calcium, may contain up to about 44 per cent 
carbon dioxide. Magnesite, a naturally occurring carbonate of magnesium, 
may run as high as 52 per cent carbon dioxide. 

The thermal decomposition of calcium and magnesium carbonates, 
for the production of lime and magnesia, is carried out on a vast scale in 
nearly all parts of the world. Gases produced in the decomposition kilns, 
used in this industry, may contain as much as 40 per cent of carbon 
dioxide by volume. This is a source of industrial carbon dioxide of 
considerable importance and many lime plants are making use of it to 
increase the profits of their companies. It is not intended to imply, how- 
ever, that every gas stream containing carbon dioxide in high percentages 
is a source of profit. Even gases containing nearly 100 per cent of carbon 
dioxide may be of little value unless the location is favorable to the existing 
or potential market. One finds a number of plants in this country making 
liquid or solid carbon dioxide from by-product gas obtained from lime or 
magnesia burning. What is said to be the largest solid carbon dioxide 
plant in the world, producing about 250 tons of the solid per day, is 
operated with carbon dioxide obtained from kilnsT* 

It is sometimes difficult to make a distinction between plants making 
carbon dioxide as a main-product and those making the gas as a by-product. 
There are, however, some plants the operation of which is adjusted to pro- 
duce as high carbon dioxide-containing gas as possible and some which are 
operated so as to produce as high-grade lime as possible. Tn the former 
case the grade of lime produced may at times be very inferior and the 
authors know of at least one plant where hand picking of the lime is neces- 
sary to produce a marketable product. 

In connection with kiln gases it might also be stated that cement kilns 
often produce gases of high carbon dioxide content. This is a potential 
supply of carbon dioxide which may become of great industrial importance. 
The authors are not aware of any plant of importance at present operating 
on such kiln gases however. 

The chemistry involved in the process of burning lime and magnesia 
will not be considered here as such a discussion belongs more properly to 
a book on that subject. 30 The removal of the carbon dioxide from the 
kiln gases produced in these operations, however, is usually accomplished 
by means of the absorption process. A schematic arrangement of such an 
absorption plant is shown in Figure 46. 

Processes producing pure carbon dioxide by the burning of carbonates 
in retorts are used for special purposes all over the world. The process of 
the Gillette Research Corporation 31 is an interesting example. This process 
is a continuous operation in which limestone, oyster shell or marble crushed 

M Knibbs, N. V. S.. "Lime and Magnesia," Ernest Benn, Ltd., London (1924). 
Gillette, E. P., U. S. Patent 1,923,084, Aug. 22, 1933. 



MANUFACTURE OF LIQUID CARBON DIOXIDE 



181 



to sizes of about to f inch, is passed into a vertical retort heated from 
the outside with oil or gas as a fuel. The preheating which takes 
place in three stages is a very important step because this eliminates all 
foreign matter such as organic material and moisture. The retorts are 
arranged so the carbon dioxide is taken from the calcining chamber as fast 
as it is produced and requires no further purification as a purity of 99.5 
per cent is easily obtained. 




FIGURE 46. Schematic Arrangement of a Plant for Making Carbon Dioxide 
from Kiln Gas. 

One's interest in carbon dioxide is usually dominated by the production 
of the liquid or the solid states, yet the large amounts of kiln gas, with 
varying amounts of carbon dioxide, used without concentration or even 
purification is also worthy of consideration. Some of the industries 
making use of such gases are: the ammonia-soda (Solvay) process for 
making soda ash and sodium bicarbonate, the refining of sugar and the 
manufacture of precipitated chalk and magnesium carbonate. 

V^ Carbon Dioxide from Dolomite. A most interesting and unusual 
method of manufacturing carbon dioxide is that used by the Crystal Car- 
bonic Laboratory in Atlanta, Georgia. This process has been described 
by Heath, 32 as a wet process in which the dolomite is treated with sulfuric 

M Heath, W. P., Ind. Eng. Chem., 22, 437 (1930). 



182 CARBON DIOXIDE 

acid, the carbon dioxide separated, the residue in the retorts which consists 
of sulfates of calcium and magnesium principally are separated and the 
magnesium sulfate in the form of Epsom salts is purified for the market. 
The dolomite used in this process is obtained from large limestone 
deposits located at Cartersville, Georgia. The average analysis is as follows : 

Calcium carbonate 54.00% 

Magnesium carbonate 45.00 

Ferrous oxide 0.05 

Alumina 0.05 

Silica 0.50 



Total 99.60 

This stone after its arrival at the plant is first prepared for the generators 
by passing it through the Sturtevant Mill Company's equipment consisting 
of a jaw crusher, ringroll mill and an air separator. This treatment reduces 
it to pass a 60-niesh screen. It is then stored above the lead-lined generators 
into which it is weighed as each charge is prepared. 

A charge for each generator consists of 1400 pounds of dolomite, 1000 
pounds of water and 2000 pounds of 60 Be. sulfuric acid. The acid is 
slowly added to the dolomite over a period of one hour and the carbon 
dioxide produced by the reaction is washed in a gas washer and sent directly 
to a large rubber gas bag having a capacity of 2500 cu. ft. which is located 
in the basement of the plant. From this gas holder it is taken to a com- 
pressor and reduced to a liquid in the usual manner, after which, it is filled 
into standard carbon dioxide cylinders for shipment. The gas produced 
by this process has an average purity of 99.5 per cent carbon dioxide the 
rest being air. 

While this process is conducted primarily for the production of carbon 
dioxide it also produces a valuable by-product in the form of Epsom salts. 
It seems evident that such a process could not compete with the coke process 
without the aid of such a by-product. 

V/BY-PRODUCT CARBON DIOXIDE FROM FERMENTATION 

In the fermentation industry, the principal chemical reaction is the con- 
version of sugar such as dextrose, into ethyl alcohol and carbon dioxide. 
This reaction is promoted by an enzyme secreted from yeast cells and its 
course may be represented by the simple equation 

C fl H 12 O fl ==2C 2 H 6 OH+2CO a . 

Theoretically, 180 pounds of dextrose will produce about 92 pounds of 
alcohol and 88 pounds of carbon dioxide. Practically, these values are not 
quite reached, because of secondary reactions and incompleteness of the 
fermentation, nevertheless, the weights of carbon dioxide and alcohol are 
usually very/iearly equal. The carbon dioxide produced in this reaction 
is largely if not completely discharged into the atmosphere in most indus- 
trial establishments. For years, attempts have been made to convert this 



MANUFACTURE OF LIQUID CARBON DIOXIDE 183 

waste product to some practical use. Joseph Priestly was perhaps the 
first to attempt its utilization. He collected the carbon dioxide from the 
top of the fermentation vats in a brewery near his home and with it 
attempted to carbonate small quantities of water. This and many other 
attempts, however, attained indifferent success from a commercial point 
of view. Gaseous impurities, and even entrained liquids and solids were 
carried by the carbon dioxide from the fermenting material and these impuri- 
ties made its use for carbonating beverages quite impossible. The gaseous 
impurities carried by the raw gas consists of aldehydes, higher alcohols and 
other compounds and these give a decidedly obnoxious odor to the gas which 
must be completely removed before the carbon dioxide can be used in food 
products. The early manufacturers, in attempting to put this by-product 
carbon dioxide on the market, failed to realize the importance of complete 
purification, with the inevitable consequence the fermentation carbon dioxide 
fell into disrepute. 

Recently, by-product carbon dioxide has assumed a much more promi- 
nent place in the industry, a condition that has resulted from the rapid 
development of uses for the solid state. Solid carbon dioxide, which but 
a few years ago, found its principal use on, the chemistry lecture table, and 
in a few cases as a refrigerant in the rescarph laboratory, developed to a 
commercial commodity with such speed that practically all sources of 
cheap carbon dioxide were utilized. The principal use for solid carbon 
dioxide is for refrigerating food products and it must, therefore, 'be with- 
out foreign odor or discoloration. To make a gas which when converted 
to the solid will meet these specifications requires the use of an elaborate 
purification process under the constant supervision of well-trained technical 
men. 



Process of Fermentation. In this country the fermentation car- 
bon dioxide industry is confined largely to the manufacture of industrial 
alcohol although one very large plant operates on carbon dioxide produced 
by the fermentation of starch to produce butanol and acetone. Immense 
quantities of carbon dioxide are produced annually in the fermentation 
industries. In 1929 something like 348,000 tons of carbon dioxide was 
produced from industrial alcohol manufacture alone in the United States. 
The present production from this and other fermentation industries must 
be many times this value. 

The fermenters in which molasses is converted to alcohol and carbon 
dioxide are immense tanks having a working capacity sometimes as high 
as 125,000 gallons. Many of these fermenters are made of wood while 
others are made of steel copper alloy. Some means of controlling the 
temperature of the fermenting mass is necessary and this is usually accom- 
plished by means of copper coils in the tanks through which cooling water 
is circulated or an arrangement for spraying the cooling water on the 
outside of the fermenters. In installations where it is desired to collect 
the carbon dioxide for purification, these fermenters are closed at the top 



184 CARBON DIOXIDE 

or in the case of certain types of wooden fermenters, a large copper hood 
is placed over them, the lower edge resting in a water seal around the top 
of the tank. These covers are provided with glass windows and an electric 
lamp inside permits the progress of the reaction to be observed. The carbon 
dioxide is discharged under a pressure of about five inches of water, first 
to the atmosphere until all of the air originally in the charge is washed out 
of the system and then to a gasometer from which it is delivered continu- 
ously to the purification system. 

The charge in a 125,000 gallon fermenter consists of 25,000 gallons of 
molasses containing about 6 pounds of sugar per gallon. The molasses is 
then diluted with 100,000 gallons of water, to which is added the yeast and 
the salts necessary for their proper growth. The period of fermentation 
may be from 40 to 60 hours and during that time, about 75,000 pounds of 
carbon dioxide is produced. The evolution of gas starts gradually, works 
up to its maximum intensity, and gradually subsides. In many cases, only 
that gas which is liberated during the period of most active fermentation is 
collected and in order to produce a continuous supply of carbon dioxide 
for the purification plant, the f crmcnters are started at definite time intervals 
and the gas stored in a gasometer of sufficient capacity to equalize the 
fluctuations in flow. 

In some cases, especially in Europe, the brewing industry also recovers 
its waste carbon dioxide for purification and compression. 33 The problems 
of purification of by-product carbon dioxide from fermenting beer mash 
ire somewhat different from those encountered in the alcohol distillery. 
In general, however, it may be said that they are solved in much the same 
manner. According to Goosmann, 34 during the manufacture of 100 gallons 
of 4 per cent beer there will be generated about 15 pounds of carbon dioxide. 
It is quite evident from these values that it requires an immense brewing 
establishment to put carbon dioxide on the market in anything like com- 
mercial quantities. 

The simple equation given above for the decomposition of sugar into 
ethyl alcohol and carbon dioxide does not account for all of the products 
of the reaction. Many secondary reactions also take place and, in addi- 
tion to the two main products just named, there are formed acetaldehyde, 
acetic acid, succinic acid, glycerol, higher alcohols, furfural and glycols. 35 
In the gases coming from fermenting beer mash hydrogen sulfide is also 
found. This is produced during the fermentation by the sulfur of the beer 
mash. Most of the sulfur comes from the sulfur containing proteins of 
barley and malt, although small amounts may be derived from gypsum or 
free sulfur. 36 ) 

Purification of Fermentation Carbon Dioxide. The removal of the 
impurities from fermentation carbon choxicle is a problem of great impor- 

Pierre, L., Brasserie et malterie, 17, 20-6 (1927). 
"Goosman, J. C., Ice and Refrigeration, 79, 295-98 (1930). 
"Farine, A., Tech. Ind. Schweis. Chcm. Ztg., 178-82 (1926). 
" Wanderscheck, Wochschr. Brau., 45, 441-6, 463-8 (1928). 



MANUFACTURE OF LIQUID CARBON DIOXIDE 185 

tance and one that is not always completely solved. There are two general 
methods of treating this raw gas and either one or both of them may be 
used depending upon the nature of the gas and the experience and prefer- 
ence of the designer. The first process removes the impurities from the 
raw gas by adsorption on some adsorbing agent such as activated charcoal 
or silica gel. The second treats the gas chemically for the oxidation of the 
impurities and removes the oxidation products other than carbon dioxide 
by means of either an adsorption or an absorption process. There are in 
operation two patented processes, namely the Backus and the Reich, the 
operating details of which are well known. It therefore seems desirable to 
go into the discussion of these somewhat in detail although it must not be 
assumed that these two processes comprehend the entire art of purifying 
by-product carbon dioxide. The largest Backus purification system yet 
installed is now operating at Deepwater, New Jersey, and the largest system 
of the Reich type at Philadelphia, Pennsylvania, yet there are a number of 
plants using systems quite different from either but employing the same 
general reactions indicated, above. 

> /THE BACKUS PROCESS OF PURIFICATION 37 

This process is essentially one of adsorption by which the impurities are 
separated on activated charcoal. One of the large distilleries using this 
process of purification is located at Curtis Bay, Maryland, and is owned 
by the U. S. Industrial Alcohol Company. 38 In this plant, fermentation If 
carried out in fifteen fermenters, each with a capacity of 125,000 gallons qf 
mash. Five of these fermenters are filled each day, therefore the daily 
carbon dioxide production of this plant must be over 180 tons. However, 
only that gas which is liberated during the period of most active fermenta- 
tion is collected, and therefore only a part of the total yield of carbon 
dioxide is utilized. 

During the period of gas collection, the carbon dioxide is taken from 
the top of the fermenters, and forced with a Root blower through a Feld 
scrubber. Here the gas is washed with water for the purpose of removing 
a large part of the entrained material, alcohol, aldehydes, etc. The impuri- 
ties still retained by the carbon dioxide are then adsorbed by passing the 
gas through purifiers filled with activated carbon. 

The purifiers are steel tanks about 3.5 feet in diameter, by 13 feet high. 
Coils of pipe inside, serve as heaters when filled with steam, or as coolers 
when cold water is circulated through them. The activated carbon is packed 
around these pipes and the carbon dioxide passes up through the mass on 
which the foreign substances are adsorbed. This adsorption has a positive 
heat of reaction ; therefore cooling becomes necessary, especially when the 
unit is first cut into the system, in order to keep the temperature of the 
carbon down to 43 to 49 C. (110 to 120 F.), at which temperature the 

U. S. Patents, 1.493,183 and 1.510,373, to Arthur A. Backus. 
Moore, W. C., Ind. Eng. Chcm., 18, 540-1 (1926). 



186 



CARBON DIOXIDE 



adsorbers are most effective. Two of these purifiers are connected in 
series and when their efficiency falls, due to the accumulation of impurities, 
they are cut out of the system and subjected to a revivification treatment. 
This is accomplished by passing live steam through the mass of carbon 
and at the same time heating it by passing high pressure steam into the 
heating coils. After all of the adsorbed material has been steamed out of 
the purifiers, the carbon is dried with a stream of warm dry air. When 
the issuing air is perfectly dry, the high pressure steam in the steam coils 
is turned off and cold water circulated so as to bring the carbon quickly 
to the proper working temperature. 

Carbon dioxide purified by this adsorption process is said to be free 
from foreign odors and to contain less than 0.1 per cent of moisture. The 
drying of the gas by the adsorbing material eliminates special drying 
apparatus and the gas can be sent directly to the compressors. 



RETCH PROCESS OF PURIFICATION 30 

This method of treatment makes use of reactions which are more dis- 
tinctly chemical than those used in the Backus adsorption process. In 
general, it is an oxidation process in which the impurities are converted by 
powerful oxidizing agents to carbon dioxide or to products which are easily 
separated by scrubbing with the proper liquids. 




A. Fermenter 

B. Catchall 

C. Alcohol Scrubber 



FIGURE 47. Reich Process. 

D and E. Water Scrubbers 

F. Gasometer 

G. Blower 

H. Bichromate Washer 



I. H a SO 4 Scrubber 
J. Soda Ash Tower 
K. Oil Washer 



The carbon dioxide taken from the top of the closed fermenters is first 
bubbled through a dilute alcohol solution in a wash box called a catch-all 
(Figure 47). This serves to remove the entrained mash, some of the 
alcohols, esters, and aldehydes, and to maintain a proper pressure on the 
fermentation vat. It is then thoroughly washed in three wooden scrubbers 
operating in series. These washers, about 30 feet high by 3 feet in diameter, 
are packed with, spiral-ring fillers. In the first tower, the gas is washed 
with a dilute alcohol solution, and in the second and third, with water to 
remove the alcohol. The wash water from the towers contains considerable 



9 U. S. Patent 1,519,932, to G. T. Reich. 



MANUFACTURE OF LIQUID CARBON DIOXIDE 187 

alcohol and it is returned to the alcohol plant where it is either distilled or 
used in the fermenters. The wash water requirement is about one gallon 
per pound of carbon dioxide treated. 

This preliminary washing removes a large part of the impurities but the 
gas still retains a trace of alcohol, ammonia, sulfur compounds and an odor 
of fermenting mash. It is then collected in a gasometer from which it is 
forced at a constant velocity by means of a blower to the rest of the purifi- 
cation train. The next step is the oxidation of the organic impurities by 
means of a solution of potassium dichromate, after which it passes into a 
sulfuric acid scrubber. The dichromate solution is contained in a tank 
through which the carbon dioxide is bubbled, but the sulfuric acid is circu- 
lated over the packing in a tower similar to that used in the first washing 
process. Any spray of sulfuric acid which may pass out of the tower with 
the gas stream is caught in another tower packed with dry sodium carbon- 
ate. This dry soda ash not only removes any sulfuric acid, but it also 
removes much of the moisture from the gas. The last washing is with 
compressor oil in a counter-current scrubber similar to the others. This 
treatment removes the oxidation products produced in the dichromate and 
sulfuric treatment. The gas is delivered to the compressors under a pres- 
sure of 2' to 3 pounds per square inch. 

It is said that this process produces an excellent grade of gas, but the 
operation requires the constant supervision of specially trained men, and is 
by no means fool-proof. 

^^COMBINATION ADSORPTION AND CHEMICAL TREATMENT 

One rather interesting installation, known to the authors, treats the gas 
under pressure by a combination of the adsorption and oxidation processes. 
One striking feature of the process is the way the treatments are given to 
the gas as it passes from one stage of the compressing operation to the next. 

The carbon dioxide is taken from the fermentation vats through a five- 
inch water seal to a storage gasometer. From the gasometer, a boosting fan 
increases the pressure to 10 inches of water and forces it through a scrubber 
where the preliminary washing takes place. From this scrubber, the gas 
goes to the first stage of a three-stage compressor, where its pressure is 
raised to about 60 pounds per square inch. After passing through an inter- 
cooler, where the heat of compression is removed, it goes to a second scrub- 
ber, where it is thoroughly washed with an alkaline solution of potassium 
permanganate. The third washing tower scrubs the gas with a sodium 
bicarbonate solution, after which it goes to the second stage of the com- 
pressor and the pressure is raised to about 250 pounds. Again the heat of 
compression is removed with an intercooler and the gas sent through a 
purifying tank filled with activated carbon. This treatment is somewhat 
similar to the adsorption process of Backus, and the final impurities are 
there removed from the gas by adsorption. After the adsorbing agent 
becomes fouled by the impure carbon dioxide it is treated in a manner 
similar to that already described for the removal of the impurities. This 



188 CARBON DIOXIDE 

revivification process, however, is needed in this process only after a con- 
siderable quantity of carbon dioxide has been purified. The third stage of 
the compressor then increases the pressure of the gas to about 1000 pounds 
per square inch and sends it to a water cooled condenser. 

When ordinary water is used in the scrubbers in which the carbon 
dioxide gas is washed, an appreciable quantity of dissolved air enters the 
system. This contamination may not be serious, as it only lowers the 
concentration of the carbon dioxide a few tenths of one per cent. For 
instance, in one plant the carbon dioxide was changed from 99.8 to 99.5 
per cent by the air carried in with the scrubbing water. However, it is 
very desirable to eliminate even this slight contamination wherever it is 
possible. One manufacturer makes use of an ingenious and interesting 
method of preventing this dilution. The liquid carbon dioxide from the 
condenser is run into a specially designed cylinder about the size of a stand- 
ard 50-pound container. A syphon tube extending nearly to the bottom of 
this cylinder, withdraws the liquid for the filling station, while any air, not 
soluble in the liquid carbon dioxide rises to the surface and mixes with the 
gas above the liquid. A bleeder pipe, connected to the top of the cylinder, 
continuously removes this gas mixture, consisting of nearly pure carbon 
dioxide and sends it back, where it is employed for deaerating the raw water 
before it is used for gas washing. The effectiveness of such a device, 
without doubt, lies largely in its deaerating action on the raw water. The 
solubility of air in liquid carbon dioxide is perhaps sufficient to prevent 
any very efficient separation in the liquid trap. Nevertheless such a device 
does improve the quality of the gas treated. This has been very definitely 
proved by analyses made on the gas when this apparatus was in operation 
and whep, it was not. 

CARBON DIOXIDE FROM BUTANOL FERMENTATION GASES 

A source of carbon dioxide of no small importance is furnished by the 
relatively new process of fermenting starch for the production of n-butanol, 
acetone and ethanol. This is the principal reaction used by the Commercial 
Solvents Corporation with plants located at Terre Haute, Indiana and 
Peoria, Illinois. In the Peoria plant the carbon dioxide is separated from 
the fermentation gases, part of it used for the production of methanol and 
the rest manufactured into the solid form and at present is being shipped 
in refrigerator cars to Dry Ice, Inc. 

Briefly the process consists in mixing corn meal and water to make 
a mixture containing about 6 to 8 per cent of the meal. This mixture is 
then sterilized with steam at 30 pounds per square inch pressure for about 
2 hours and after cooling is charged into closed fermenters of about 50,000 
gallons capacity. The fermentation which requires from 48 to 72 hours 
is accomplished by means of a special ferment (Clostridium acetobuty- 
licum), and the gaseous products of the reaction, which are produced at 
a maximum rate of about 8,000 to 10,000 cubic feet per hour, are 



MANUFACTURE OF LIQUID CARBON DIOXIDE 189 

collected. 40 One hundred pounds of starch will, under favorable conditions, 
produce 33.3 pounds of mixed solvents, containing about 60 per cent 
n-butanol, 30 per cent acetone and 10 per cent ethanol, and SO pounds of 
gas, consisting of hydrogen 45 per cent by volume and carbon dioxide 55 
per cent by volume. Thus from 100 pounds of starch one may expect 
20 pounds of butanol, 10 pounds of acetone, 3.3 pounds of ethanol, 1.767 
pounds of hydrogen and 48.23 pounds of carbon dioxide. 41 

.The gaseous product of this reaction is easily separated into its constitu- 
ents. The crude gas is first passed through a charcoal adsorber in which 
the solvent vapor content, amounting to about 30 grams per 100 cubic feet, 
is removed by adsorption. The hydrogen is separated from the carbon 
dioxide by sending the gas at 250 pounds per square inch pressure through 
an absorption tower counter-current to a stream of water. The carbon 
dioxide is nearly all absorbed and the residual hydrogen, after passing 
through a caustic tower, is pure enough for making ammonia or methanol. 
On releasing the pressure over the water solution of carbon dioxide the gas 
separates carrying with it about 3 per cent hydrogen. A part of this impure 
carbon dioxide, which is not used for making synthetic methanol, is 
delivered to the dry ice plant where it is liquefied, passed through a series 
of rectifiers and the separated hydrogen returned to the methanol plant. 

AND TRANSPORTATION OF CARBON DIOXIDE 



The rate at which the carbon dioxide industry developed was controlled 
to a large extent by two factors ; one the production of compressing appar- 
atus for reducing the gaseous compound to a liquid and the other the 
development of tanks for holding the product. This latter phase of the 
industry is far more important than one might expect from a casual inspec- 
tion. The problem is one of obtaining a steel tank or bottle sufficiently 
strong to withstand the high pressures under all conditions met with during 
transportation and use of this product. While there have been on the 
market at various times in the past cylinders of many sizes and shapes, these 
have now narrowed down to a few standard sizes, the most important of 
which are those of 50 and 20 pounds capacity. Others holding 5, 3 and 0.75 
pounds of carbon dioxide are used mostly for medicinal purposes and as 
portable containers for use in automobiles etc. The manufacturer is inter- 
ested mostly in the first two sizes as these are the containers into which most 
of his product is compressed. The method of making these steel cylinders 
is one of the most interesting metallurgical processes but a consideration of 
it here would, perhaps, be quite out of place. 42 

The condition and behavior of carbon dioxide while in a cylinder should 
concern everybody who has occasion to handle or use this substance. It is 
well known that the cylinder contains liquid and gaseous carbon dioxide 
but the relative proportions in which these exists, the influence of over- 

"Killeffer, D. H., Ind. Eng. Chem., 19, 46-50 (1927). Woodruff, J. C., Ind. Ena. Chem. 19, 
1147-50 (1927). 

41 Gabriel, C L. f and Crawford, F. M.. Jnd. Ena. Chcm., 22, 1163-5 (1930). 
Minor, J. C., Ind. Eng. Chcrn., 4, 88-96 (1912). 



190 CARBON DIOXIDE 

filling and the effect of impurities on the pressure are not so well known. 
Stewart, 43 some years ago, made a most exhaustive study of this question 
and developed methods and equations for designing these cylinders in order 
to obtain the maximum protection for those handling them while at the 
same time producing a cylinder of minimum weight. 

The desirability of filling a cylinder to the limit of its capacity is unques- 
tioned, on the other hand, over-filling is considered bad practice because 
of the decrease in the safety factor. The coefficient of expansion of liquid 
carbon dioxide is high and a cylinder completely filled with the liquid at 
temperatures considerably below the critical point has to withstand the 
hydrostatic pressure of the liquid when temperature increases occur. How- 
ever, when part of the cylinder volume is occupied by liquid and the rest by 
the gas, then the pressure exerted on its walls is that of the vapor pressure 
of the liquid which changes in a moderate manner with a change in temper- 
ature. Increasing the temperature causes some of the liquid to evaporate 
thus decreasing its volume but this increase in temperature, because of the 
thermal expansion of the liquid, tends at the same time to increase the liquid 
volume. Thus we have two forces operating in opposite directions with the 
result that the volume of liquid increases if the thermal expansion predom- 
inates or decreases if the evaporation predominates. Which of these exerts 
the most influence depends upon the relative proportion of gas to liquid 
in the cylinder. Thus it is possible to have a cylinder only partly filled with 
liquid and by an increase in temperature cause it to be completely filled. 

The effect of over-filling on the pressure of carbon dioxide in a cylinder 
is shown by the figures taken from table in Ullmann's work. 44 The pressure 
of carbon dioxide in atmospheres for normal and over-filled cylinders : 

Temp. 
C. 



5 

10 
15 
20 

25 
30 
35 
40 
45 

Above the brackets the pressure is the vapor pressure of the liquid, in the 
brackets the pressure is the hydrostatic pressure of the liquid and below the 
brackets^ is the gas pressure of the substance above its critical temperature. 
Figure 48 shows the behavior of liquid and gaseous carbon dioxide 
under different degrees of cylinder filling. This diagram plotted by Stewart 

43 Stewart, R. T., Trans. Am. Soc. Mcch. Entj. t 30, 1111 (1908). 

44 Ullman, F.. "En/ykloparlie dcr tcchnischen Chemie," 5, page 693, Urban and Schwarzen- 
berg, Berlin (1919). 



Normal 
filling 
1 kg. in 
1.341. 


5% over 
filling 
1.05 kg. in 
1.341. 


10% over 
filling 
1.1 kg. in 
1.341. 


34.4 atm. 


34.4 atm. 


34.4 atm. 


39.5 


39.5 


39.5 


450 
51.2 
57.8 


45.0 
51.2 


45.0 


| 54.7 


| 65.4 


75.6 
99.0 
119.3 


77.3 
97.7 


88.5 
109.1 


115.5 


126.9 


137.2 


137.2 


149.7 


160.7 


159.0 


172.7 


185.1 



MANUFACTURE OF LIQUID CARBON DIOXIDE 



191 




TOmperafure *C> 

FIGURE 48. The Relative Proportion of Liquid and Gaseous Carbon Dioxide 
in Cylinders Under Different Degrees of Filling. 




. 6 ^7 

Combined Oeniti Temperature 4-Qjsfc. 

FIGURE 49. Showing how Impurities Affect the Pressure of 
Liquid Carbon Dioxide. 



192 CARBON DIOXIDE 

shows that if the combined densities of liquid and gas is less than the critical 
density (0.464) then the liquid will decrease in volume if the temperature 
is increased while if the combined densities is greater than the critical 
density then an increase in volume will result with an increase in tempera- 
ture. In other words, if the cylinder is filled so that it is 50 per cent or 
more liquid then an increase in temperature will cause an increase in volume 
of liquid but with less than SO per cent liquid in the cylinder a decrease 
in its volume will take place if the temperature is increased. Stewart con- 
sidered that under normal conditions of use it is safe to fill a cylinder to 
60 to 62 per cent of its volume with liquid. Fillings up to 75 pef cent have 
been permitted but this high value is now considered unsafe. It might be 
added, that very strict regulations are made by the Bureau of Explosives 
for the filling and handling of all cylinders of carbon dioxide which are 
shipped by common carriers. Inspectors from time to time check on the 
weight and purity of gas found in manufacturing plants. 

How gaseous impurities, especially air, affect the pressure exerted by 
liquid carbon dioxide is clearly shown by the curves in Figure 49. These 
curves, also by Stewart, are plotted so as to show the effect of various 
amounts of gaseous impurities and are plotted from the measured pressures 
found at different degrees of cylinder filling. 



Chapter VII 

Manufacture and Distribution of 
Solid Carbon Dioxide 

Although carbon dioxide in the solid form has been applied to laboratory 
problems to some extent during the past century its industrial application 
for refrigeration extends back only a comparatively few years. Perhaps the 
first suggestion that solidified carbon dioxide might find application in 
commercial refrigeration is found in the patent specifications of Tichborne 
and Elworthy. 1 About the year 1907 Newth 2 made this most interesting 
comment concerning the solid carbon dioxide industry in England : " 'Car- 
bonic acid snow/ as this substance is sometimes termed, is now an article 
of commerce, the compound being sent into the market in this form to avoid 
the cost of the carriage of the necessarily heavy steel bottles containing the 
liquid." In 1922 Reich 3 made some semi-commercial experimental batches 
of this material and proposed its use for railway refrigeration but no further 
commercial exploitation of the idea was then made. To Josephson and 
Slate must be accorded the credit of first realizing the advantages of solid 
carbon dioxide as a commercial refrigerant. In 1924 they proposed to sell 
and actually did commence to sell solid carbon dioxide in New York City 
for refrigerating ice cream. The ice cream industry also soon became aware 
of the many advantages of this refrigerant such as compactness, freedom 
from moisture, improved insulation efficiency and the changes in package 
and truck design possible, with the result that its use became gradually 
extended until today tremendous quantities of this solidified gas is being 
made and sold. 

Before turning to a detailed description of the commercial manufacture 
of solid carbon dioxide, more popularly known as dry ice, it might be well 
to devote some attention to the relative importance of manufacture and 
distribution. 

In general, it may be said that efficient distribution is a more important 
factor than efficient manufacture in the solid carbon dioxide industry of 
today. The fact that evaporation of solid carbon dioxide proceeds from the 
moment of its manufacture, introduces distribution problems not usually 
found in other commercial products. It is obvious that evaporation losses 
will be decreased as the point of production is brought closer to the point 

1 Tichborne, C. R. C., Brit. 13,684 (1891). Elworthy, H. S., U. S. 579,866 and Brit. 7,436 (1895). 
a Newth, G. S., "A Text- Book of Inorganic Chemistry," page 307, Longmans. Green and Co. 
London (1907). 

"Reich, G. T., Chcm. Met. Rng., 38, 270 (1931). 

193 



194 CARBON DIOXIDE 

of ultimate consumption. It is also evident that the evaporation loss 
depends upon the mass of material handled as a unit and that the smaller 
the unit the greater the percentage of material vaporized. It is also at once 
apparent that for each complete set of supply conditions an optimum con- 
tainer design can be reached in which the saving of evaporation loss gained 
through effective insulation and correct container construction, would be 
sufficient to justify the necessary investment. It is further apparent that 
the selection of the point in the distribution chain at which bulk is broken 
in each specific case is of vital importance. 

The standard size for solid carbon dioxide blocks, in this country, is 
10x10x10 inches weighing from 52 to 55 pounds when freshly manu- 
factured. Immediately on leaving the press or cutting saws these blocks 
are wrapped or bagged in Kraft paper and packed into shipping containers. 
For small requirements the blocks are shipped singly by express or truck 
in corrugated paper cartons augmented either with corrugated paper liners 
and pads, with fibrous insulation materials, or with multiple paper wrap- 
pings. Any one of these methods of packing is usually sufficient to reduce 
the evaporation loss under average summer conditions to 8 pounds or less 
per block during the first 24 hours. Such containers are usually discarded 
after one use, and hence their prime requisite is low cost. For regular 
shipments in larger quantities, boxes holding 2, 4, 6, 8, 12, 36, 45 and 120 
standard blocks are commercially available. Some of these containers are 
illustrated in Figure 50. 

The complication of the distribution problem and its paramount impor- 
tance to the commercial success of the industry, has led to the growth of 
two schools of thought. One seeks to escape the heavy costs of evaporation 
losses and distribution by locating plants of minimum size as close to the 
market as possible, in some cases sacrificing the transportation saving by 
the added costs of producing on a small scale. The other school seeks to 
escape the heavy costs of small scale production by manufacturing in central 
plants of large daily capacity. This naturally necessitates shipment for 
longer distances in search of a market and in some cases sacrifices the sav- 
ing in plant cost by higher evaporation and transportation costs. It is 
apparent that in any such situation generalities fail and local conditions 
determine the choice in each case. 

It may be said that a rational consideration of a solid carbon dioxide 
manufacturing project should take the following order : 

1. Thorough survey of markets and accurate mapping of tonnages 
expected to be sold in each, for each month of the year. 

2. Calculation from (1) above of the probable evaporation losses and 
transportation costs. This enables a calculation of the number of 
extra tons which must be manufactured annually to cover losses 
and the probable burden of transportation costs which must be car- 
ried regardless of the merits of the source of carbon dioxide per se. 

3. Survey of costs of power, water, labor and carbon dioxide at the 
proposed plant site. 



MANUFACTURE OF SOLID CARBON DIOXIDE 195 

4. Determination from these data whether the cost at the production 
point is low enough to bear the necessary burdens of evaporation 
and distribution costs. 




FIGURE SO. Shipping Containers for Solid Carbon Dioxide. 

It is perhaps, quite evident that there is no best scheme for manufacturing 
solid carbon dioxide and that the selection of plant location and process 



196 CARBON DIOXIDE 

should be arrived at, in each instance, after thorough engineering study of 
all ascertainable facts bearing on the situation. It is well, however, to 
emphasize that the history of American ventures in solid carbon dioxide 
clearly indicates the importance of distribution and its ascendency over" the 
chemistry and thermodynamics of solidification. 

^/ REFRIGERATING CYCLES 

Improvement in the refrigerating cycles, as applied to solid carbon diox- 
ide production, has engaged the attention of refrigerating engineers for 
some time. Without doubt this interest has been stimulated largely by the 
fact that the refrigerating cycle affords the only opportunity in solid car- 
bon dioxide manufacture for the specific exercise of the refrigeration art. 
These studies, however, have resulted in considerable advantage on the 
whole to the solid carbon dioxide industry. 

The Simple Cycle. The starting point in the development of solid 
carbon dioxide manufacture is the simple cycle used for many years in the 
preparation of solid carbon dioxide for the laboratory. Liquid carbon 
dioxide, made by any of the methods already described, is expanded into 
a bag made of cloth or chamois leather and the heat of vaporization, taken 
largely from the liquid, converts part of it into "snow." The yield of 
"snow" obtained by this method naturally depends upon the initial tem- 
perature of the liquid and the efficiency of the heat transfer during the 
reaction. For all practical purposes commercial liquid carbon dioxide may 
be considered as a pure compound and in a saturated condition and it may 
be treated successfully in thermodynamical calculations for the determina- 
tion of yields of solid. Therefore the amount of solid obtained by simple 
expansion or even a series of such expansions may be taken directly from 
the P-I diagram by assuming expansion at constant total heat. 

A most convenient diagram prepared by Stickney 4 and given here as 
Figure 51, shows at a glance the yield of solid carbon dioxide obtainable 
from a definite weight of liquid or saturated vapor. Thus if one starts 
with 1 pound of saturated liquid at 70 atmospheres pressure and about 
84 F. and expands it adiabatically to 1 atmosphere, a yield of 0.230 pounds 
of the solid will be obtained. Tf, however, the liquid carbon dioxide is 
first flashed to 20 atmospheres a yield of 51 per cent or 0.510 of liquid 
will be obtained at a temperature of about 2 F. Now if this liquid is 
again flashed to the triple point 0.297 pound of solid will be produced and 
on further decreasing the pressure to one atmosphere a yield of 0.230 pound 
of solid will remain. 

It is evident from these figures that no matter what the intermediate 
processes may be the ultimate yield of solid will be the same in all cases. 
Therefore any advantages obtained by more elaborate methods such as will 
be described later, will be gained by returning the vapor to the compres- 
sion system at pressures above atmospheric or hv taking advantage of 
the cooling effect of the vapor from the snow machines. 

Stickney, A. B.. Refrigerating Eng. t 23, 334-42 (1932). 



MANUFACTURE OF SOLID CARBON DIOXIDE 



197 




8218SS88S8S8 S s t s s * 

saaaHdsowiv - r * 



198 CARBON DIOXIDE 

Many of the small manufacturers of solid carbon dioxide today employ 
only the simple, inefficient and rather primitive refrigeration cycles, rather 
than the more complicated and refined systems described below. In most 
cases the savings from decreased leakage, easier regulation, greater safety, 
smoother operation, less investment and less expensive labor is more than 
adequate to offset the waste of power. In general, it may be said that only 
large capacity units operating with assurance of sufficient tonnage for sus- 
tained operation at heavy rates, can afford to entertain the more compli- 
cated and theoretically more efficient cycles. 

Preceding Cycle. 5 The first improvement on the simple cycle was 
disclosed in the patents of Elworthy and Henderson, who introduced a 
heat exchanger, by which a portion of the sensible heat of the liquid carbon 
dioxide leaving the condenser is transferred to the cold carbon dioxide gas 
leaving the solidification apparatus. 

Bleeder Cycle. This cycle is so named because of the fact that some 
of the carbon dioxide vapor is bled from the system at some reduced pres- 
sure and returned to the compression system. If 1 pound of liquid at 70 
atmospheres pressure and about 84 F. (as in the illustration given above) 
is run into a tank, called a flash tank, evaporator or accumulator, main- 
tained at a pressure of 20 atmospheres, then 49 per cent of the liquid will 
evaporate. This vaporization will produce 0.490 pound of saturated vapor 
at a temperature of about 2 F. and a pressure of 20 atmospheres. This 
vapor can then be sent to the compressor and introduced at some inter- 
mediate stage for recompression. 

This method of cooling liquid carbon dioxide by flashing from a higher 
to a lower pressure found its principal application and development in the 
mechanical refrigeration art and seems to have been first proposed by 
Linde and Lightfoot. 7 Windhauscn 8 improved upon Linde and Lightfoot's 
system by the use of a dual effect compressor, equipped with two sets of 
suction ports through one of which high pressure vapor from the evapora- 
tor is passed. This made it possible to use one cylinder instead of two 
for compressing vapor received at two different suction pressures. This 
principle was further improved by Voorhees, 9 who arranged his auxiliary 
suction, receiving vapor from the primary evaporator, in the form of ports 
in the cylinder wall midway of the piston stroke. 

Various devices have been used for automatically feeding the liquid 
carbon dioxide to the evaporators such as, for example, the float valve 
invented by Brier 10 and shown in Figure 52. These devices, however, 
operate more successfully on the carbon dioxide refrigerating machines 

5 The nomenclature of the refrigerating cycles Riven here and the general treatment of their 
comparative efficiency is based on the excellent paper by Stickney, Loc. cit. 

9 Elworthy, H. S. f and Henderson, P. D. f Brit. 7436 (1895). 
T Linde, C., and Lightfoot, Brit. 1875 (1890). 
8 Wndhausen, F., Brit. 9084 (1901). 

Voorhees, G. T., U. S. 793,864 and Brit. 4448 (1905). 

10 Brier, Henry, U. S. 1,452,999 (1918). Goosmann, J. C., and Zumbro, F. R., Refrigerating 
Eng., 16, 1 (1927). 



MANUFACTURE OF SOLID CARBON DIOXIDE 



199 



than in the solid carbon dioxide manufacturing system because in the latter 
case the presence of water often seriously interferes with their operation. 
In the solid carbon dioxide industry hand regulation of the feed of carbon 
dioxide to the evaporators is the most usual practice. 



FIGURE 52. 
Brier Evaporator. 




Bleeder-Precooling Cycle. In both the "bleeder" and the "snow- 
making" cycles, liquid carbon dioxide is fed to the solidification machine 
under its own vapor pressure. When the liquid is fed to the snow-making 
machine at a temperature near its triple point considerable difficulty is 
encountered because of the clogging of the nozzles with solid carbon diox- 
ide. This can be overcome by combining the bleeder and precooling cycles 
and delivering the liquid carbon dioxide to the expansion nozzles under 
a full condenser pressure. The liquid from the water cooled condensers 
is separated into two parts. One part of this liquid is expanded into heat 
exchangers, usually arranged in two units, and the resulting vapor is 
returned to the compressor system. The other part of the liquid carbon 
dioxide is sent through the inner coils of the exchangers where the tem- 
perature is lowered to any desired point. 

Pressure Snow-Making Cycle. In many of the large solid carbon diox- 
ide plants in this country, where automatic presses are used, the snow is 
made in the press chamber at the triple point and the pressure is reduced to 
atmospheric on the completed block. It is customary in plants of this kind 



200 



CARBON DIOXIDE 



to have a separate compression system to handle the return vapor from 
the snow machine and the evaporators. This is often called the recom- 
pression system. The liquid carbon dioxide is expanded into the evapora- 



Snow 
Chamber 




UU 
Snow 

SIMPLE CYCLE 



Make Up Gas 



NH 3 Condenser 
Receiver 

NH 3 Evaporator 
C0 e Condense i 



Exp Valve 
5now Chamber 






* i 

Inter Cooler r 

~K 





Snow Make U 

BINARY CYCLE 




I 



tf vtfviuu Make Up Gas 

C Snow 

f BLEEDER PRECOOLING CYCLE 



Condenser 

Exp. Valve 
Flash Tank 
Exp. Valve 
Snow Chamber 




Make Up Gas 

Snow r 

PRESSURE SNOW MAKING CYCLE 



Condensei 

1C 

Exp. Valve 
FlashTanl 




Condenser 



Snow Chamber 



TMTSnow 

BLEEDER CYCLE 



Make Up Gas 




TUT 

Snow 
PRECOOLING CYCLE 



Make Up Gas 



FIGURE 53. Flow Diagrams of Six Types of Carbon Dioxide Cycles. 

tor where the vapor is returned to the recompressor and enters at the suc- 
tion port of the high stage of a three-stage compressor, or when a four- 
stage machine is used, at a point where the suction pressure is approxi- 
mately 250 pounds per square inch. The cooled liquid is then expanded 
into the snow chamber at a pressure below or at the triple point and after 



MANUFACTURE OF SOLID CARBON DIOXIDE 201 

the snow block is formed the return gas is sent to the suction of the low 
stage and the pressure above the block is reduced to atmospheric. 

Binary Cycle. In this cycle the liquid carbon dioxide is cooled by 
means of an auxiliary refrigerating machine. When ammonia is used as 
the refrigerant considerable thermal advantage is gained over carbon diox- 
ide. This is due to the fact that ammonia is a more efficient thermody- 
namic medium than carbon dioxide, over the range considered, because of 
the fact that carbon dioxide is working so near its critical temperature. 
The evaporator of the ammonia refrigerating machine serves as a con- 
denser for the carbon dioxide system. It is thus possible to operate the 
entire system at a pressure below 25 atmospheres. Since ammonia leak 
detection is simpler and more reliable than carbon dioxide leak detection, 
the result is a system easier to operate with a minimum loss by leakage. 
Where a value must be assigned to the carbon dioxide, this becomes an 
important consideration. Indeed, where gas valuation is high, it is thf> 
controlling one. 

These cycles are illustrated diagrammatically in Figure 53 which clearly 
distinguishes them. Other combinations are possible, of course, but these 
six types include all that have been used commercially to any extent, others 
being variations of detail following the same principles. Thus, the intro- 
duction of multiple effect compression may increase the stages of com- 
pression from three to six and the number of evaporators in the bleeder 
cycle from two to five but thus far such variations have had little appeal 
to manufacturers because of the added cost and complication. 

For each of these six typical cycles, given a definite knowledge of the 
condenser pressure employed, and the temperature of the liquid carbon 
dioxide delivered by it, calculation of power consumption is readily made 
by the conventional formulas assuming adiabatic compression. 11 Power 
consumption can also be readily approximated by plotting the cycle in ques- 
tion on a temperature-entropy diagram and measuring the area included. 

An interesting comparison of power consumption of the above described 
cycles was made by Stickney, based on the following assumptions : 

(1) Three stage compression. 

(2) Adiabatic compression in each stage. 

(3) Make-up gas supplied at 1 atmosphere. 

(4) Temperature of make-up gas same as temperature of liquid attain- 
able by exchange with cooling water. 

(5) Intercooling to 10 F. above the final liquid temperature. 

(6) Terminal temperature difference in gas-to-liquid heat exchangers 
20 F. 

These comparisons are made in English units and arc based on the thermal 
data of Plank and Kuprianoff. 12 

11 Ford, J. M., "Compressor Theory and Practice," Constable (1923). Macintire, II. J., "Hand- 
book of Mechanical Refrigeration," Jonn Wiley and Sons, New York (1928). 

M Plank, R., and Kuprianoff, J., "Die thermischen Eigenschaften der Kohlensaure im gas- 
formigen, flussigen und festen Zustand," Ges. f. Kaltcwesen, m.b.II., Berlin (1929). 



202 



CARBON DIOXIDE 



Figure 54 shows the temperature-entropy diagrams for these cycles, 
each step in each cycle being readily understood by reference to Figure 53, 
the numerals corresponding throughout. Thus, in the simple cycle, the 
element between 2 and 3 in the flow diagram is obviously the first or low- 
pressure stage of compression, while the line 2-3 on the T-S diagram indi- 



BLEEDER 
PRECOOLING CYCLE 




FIGURE 54. T-S Diagrams for Carbon Dioxide Cycles. 

cates this operation, followed by 3-4 which on both diagrams in this 
instance indicates intercooling by water, 4-5 the second stage of compres- 
sion, 5-6 the second intercooling, 6-7 the third compression stage, 7-8 the 
condensation and so on. Since all of the cycles may be clearly traced in 
this manner it does not seem necessary to traverse each one in detail. 



MANUFACTURE OF SOLID CARBON DIOXIDE 



203 



It is obvious that for each of these cycles, the power consumption in 
manufacturing solid carbon dioxide will vary with the selection of inter- 
mediate and final pressures in the compressor system, with the tempera- 
ture of the condensing water and the efficiency of the condensers. 13 

Stickney's calculations of the power consumption in each cycle are 
given in Figure 55. Here the power consumption in kilowatt hours per 
ton of solid produced is plotted against the liquid temperature. The dia- 
gram also shows the efficiency of each cycle in terms of per cent of Car- 



A- Simple. So*. | 

a- - opt ' 

8- Prvcool- Sot. 
- - - Opt. 
C-BIdr-Sot. 

r- - opt. 

_G-Bledr-Prcool 
^ 




Liquid Temp. Liquid Temp. 

FIGURE 55. Efficiency of Carbon Dioxide Cycles. 

not cycle efficiency as a function of liquid carbon dioxide temperatures. In 
the case of the simple, prccooling and bleeder cycles two efficiency curves 
arc given, one assuming that the head pressure on the compressor system 
is held to a minimum (i. e. saturation pressure) and the second assuming 
that higher head pressures are carried equivalent to theoretical optimum 
pressures as calculated by Stickncy. Such higher pressures are sometimes 
loosely rcferrgctto as- "follow-up" pressures. 




PREPARATION OK CARBON DIOXIDE FOR SOLIDIFICATION 

The purification of carbon dioxide for the liquid trade has already been 
considered and this operation in the solid industry adds no new problems. 
A plant manufacturing carbon dioxide for sale in cylinders can convert 
this liquid to the solid state without further treatment. There are, how- 
ever, many plants manufacturing solid carbon dioxide as their only product 
and in such cases it is desirable to determine just how much purification 
is necessary. 

18 For a consideration of the factors affecting the selection of optimum head pressures, see 
Stickney, Loc. cit. 



204 CARBON DIOXIDE 

Removal of Permanent Gases. In all commercial plant operations 
known to the authors, the raw material for the solid carhon dioxide pro- 
duction is at least 99.5 per cent carbon dioxide, with one exception, the 
plant of Dry Ice Corporation in conjunction with the Commercial Solvents 
Corporation's operation at Peoria, Illinois. In this plant as has already 
been noted the carbon dioxide is furnished to the dry ice plant at approxi- 
mately atmospheric pressure and containing from 4 to 5 per cent of hydro- 
gen. A separation of the two gases is easily made by means of a frac- 
tionating column. There seems to be, however, little tendency to make use 
of this method for separating inert gases in other plants. 

Removal of Water. In the consideration of methods of removing 
water from carbon dioxide in the manufacture of solid carbon dioxide, the 
first question to be determined is whether it is advisable to remove water 
at all. This is a question which can be decided only in the light of the 
conditions existing in particular plants and must be viewed from four gen- 
eral aspects : 

(1) Structure of Product. There is considerable evidence to indi- 
cate that finely divided crystals of water ice dispersed through a block of 
solid carbon dioxide, modify its structure to a considerable extent. The 
water can be presumed to function as an intercrystalline impurity and no 
doubt exerts some bonding effect but more prominently it serves to inter- 
fere with the growth of the crystals of pure solid carbon dioxide so that 
an extremely dry product is considered more likely to become "sugary" 
from crystal growth. Josephson 14 claims definite advantages in the use of 
solid carbon dioxide refrigerant to which water has been deliberately added. 
Although the special properties of solid carbon dioxide containing con- 
siderable proportions of water snow have not proved desirable in commer- 
cial applications up to this time, there is no question that such a product 
behaves differently from dry solid carbon dioxide, and it is possible that 
these differences may prove desirable in some cases. 

(2) Corrosion. Moist liquid carbon dioxide is an active corrosive 
agent in the presence of oxygen, but in the absence of oxygen is not appre- 
ciably corrosive. The best evidence of this fact is the use of mild carbon 
steel cylinders for the transportation of liquefied carbon dioxide and the 
fact that, due entirely to the limited supply of oxygen, corrosion is nominal 
in most cases even after these cylinders have been used for periods of as 
much as a quarter of a century as containers for moist liquid carbon diox- 
ide. It seems probable that under these conditions corrosion continues 
until any free moisture present becomes saturated with ferrous bicarbonate, 
when corrosion ceases except to the extent that oxygen is available for 
its continuance. 

A practical solution for the corrosion problem in solid carbon dioxide 
manufacture most often lies either in eliminating oxygen from the sys- 
tem, or in keeping any oxygen which may enter the system at the ice 

"Josephson, W. S., U. S 1,873,131 and co-pending applications, Refrigerating Eng. t 19, 
25-6 (1930). 



MANUFACTURE OF SOLID CARBON DIOXIDE 205 

presses, separated from moisture which may enter with the supply of raw 
carbon dioxide. Where thorough drying is employed, however, corrosion 
is eliminated in all parts of the system reached only by dry product. 

(3) Stoppages. It is obvious that, where temperatures below the 
freezing point of water exist in the refrigerating cycle, excessive quantities 
of water will cause difficulty with freeze-ups. This may cause serious inter- 
ference with operation and necessitates careful drying where the more com- 
plicated low-temperature refrigerating cycles are employed. Many plants, 
however, adhere to the use of the simple cycle, or refrigerate their liquid 
carbon dioxide only to temperatures above 32 F. in cycles of the pres- 
sure snow-making type, thus escaping any necessity for the drying opera- 
tion on the score of stoppage. 

(4) Odor Removal. Where moist carbon dioxide gases such as fer- 
mentation by-product gas, are to be handled, removal of water vapor from 
the gaseous carbon dioxide generally results in condensing odorous mate- 
rial along with the water. This drying operation would naturally improve 
the quality of any gas containing any appreciable quantity of water-soluble 
odorous impurities. 

The methods used for removing water from carbon dioxide in the 
manufacture of the solid differ in no essential way from those already dis- 
cussed for drying liquid carbon dioxide. One method of interest, which 
perhaps is not practical in the liquid industry, is described in the patent 
of Jones. 15 In this process water is separated in the solid instead of the 
liquid phase by the evaporative cooling of liquefied carbon dioxide to tem- 
peratures 'below the freezing point of water and by the filtration of the 
resulting "sleet" through a filter bag, which retains frozen carbonated water 
ice and which permits relatively dry liquid carbon dioxide, still carrying 
a trace of dissolved moisture, to pass through it. 

STRUCTURE OF SOLID CARBON DIOXIDE 

Before proceeding to a discussion of the various devices for the com- 
mercial solidification of carbon dioxide it might be well to refer briefly to 
the structural form of the finished product. This is of importance, from 
a practical point of view, only to the extent that it affects the resistance 
of the product to mechanical injury and its behavior as a refrigerant on 
sublimation. 

It is perhaps evident that a block of solid carbon dioxide to give satis- 
faction to the trade must be hard, compact and not too brittle. To attain 
this condition is not very difficult and is usually accomplished by giving 
attention to the pressing operation. It may be said that any method which 
places an evenly distributed charge of solid carbon dioxide in a chamber 
and compresses it to a desired predetermined density, will give a product 
which is entirely satisfactory if it is quickly utilized. 

The differences existing between the various methods of manufacture, 
in so far as the structure of the product is concerned, become apparent 

"Jones, C. L., U. S. 1,873,418 (1932). 



206 CARBON DIOXIDE 

only after extended storage or after shipping over considerable distances. 
As such conditions are found only in the United States it is not yet pos- 
sible to make a comparison of the European methods and machines from 
this point ot^iew. 

V METHODS OF SOLID CARBON DIOXIDE FORMATION 

The process of producing solid carbon dioxide merely consists of the 
removal of sufficient heat from the gaseous and liquid forms to reduce the 
product to a solid state. This may be accomplished by proceeding along 
any of the lines used for the solidification of other materials, if the availa- 
bility of the necessary apparatus be presumed. 

The general type methods may be classified as follows : 
I. By transfer of heat to external refrigerating means. 

A. By the freezing of liquefied carbon dioxide under pressure, heat 
being transferred from the carbon dioxide through the walls of 
its container to refrigerating means at temperatures below its 
triple point. 

1. With "follow-up" pressure on the liquid in order to fill voids 
caused by freezing contraction. 

2. Without "follow-up" pressure. The product in this case has 
a porous core. 

B. By the freezing of carbon dioxide out of gas mixtures. 

1. By condensation on cold surfaces. 

2. By fractional condensation from gas mixtures by expansion. 
IT. By self-evaporative cooling, in which the solidification of a portion of 

the carbon dioxide is effected by the vaporization of the remainder. 

A. Through evaporation of a bath of liquefied carbon dioxide with- 
drawing evolved vapor only from above. 

1. By very slow evaporation, adherent and fairly dense prod- 
ucts may be made without subsequent pressing. 

2. In the more common practice, the boiling is conducted more 
rapidly to produce a porous mass of crystals which are sub- 
sequently pressed. 

B. By expansion of liquefied carbon dioxide directly to pressures 
below or at its triple point to produce "snow," which is subse- 
quently pressed or tamped to produce commercial blocks. 

1. By formation of snow in one apparatus and its removal, 
redistribution, and pressing in a second apparatus. 

2. In self-contained presses in which deposition and pressing 
take place in the same chamber. 

C. By expansion of liquefied carbon dioxide with performance of 
external work for the purpose of increasing the yield of solid 
by more nearly isentropic expansion. 

D. Deposition of solid progressively upon a filter or screen through 
which carbon dioxide gas is withdrawn partly or wholly down- 
ward through the mass already formed. 



MANUFACTURE OF SOLID CARBON DIOXIDE 20', 

1. Pressure above the solid held below the triple point. The 
product in this instance is merely a dense snow more or less 
compacted by gas pressure and is of practical value prin- 
cipally in pellet machines, where the piece is so small that 
mechanical properties are comparatively unimportant. 

2. Pressure maintained in the neighborhood of the triple point, 
involving production of so-called "moist" snow or "slush." 

3. Pressure above the solid maintained in excess of the triple 
point, maintaining more or less liquid above the solid already 
formed, producing a mass of inspissated material in which 
crystal growth may readily be caused to proceed to lengths 
as great as 10 cm., but naturally limited in density by the 
necessity of sufficient downward permeability through the 
mass for continued escape of vapor. 

It should be noted that not all of the above classifications are mutually 
exclusive. Thus it is theoretically possible to combine them in various 
ways, for example, snow may be deposited by expanding the liquid to pres- 
sures below the triple point as in IT-B and then increasing the pressure 
and subjecting the mass of snow to downward flow of gas as in TI-D-1, 2, 
or 3 to increase its density. 

Again, it must be noted that the above type methods of solid forma- 
tion bear no necessary relation to individual types of equipment. One 
type of press employed in American practice may be employed without 
physical alteration of the press construction for the performance of any 
desired one of the eight type methods listed under II and no doubt certain 
other presses among those described below would lend themselves, if 
desired, to operating under other solid formation technic than that recom- 
mended by the manufacturers of the devices as preferable. 

For an extended theoretical discussion of certain of these general type 
methods, the reader is referred to the patent literature listed in the appen- 
dix of this book, and to Kuprianoff's discussion and report of small scale 
experiments. 10 

The description following will be confined to tracing the evolution of 
commercial solid-forming equipment now used in the solid carbon dioxide 
industry. 

DEVELOPMENT OF AMERICAN PRESS EQUIPMENT 

The Snow Tank. The first machine employed by the Drylce Cor- 
poration, and indeed the machine in which all the solid carbon dioxide of 
commerce was manufactured for some time from the beginning of the 
industry, was the snow tank of Martin. 17 In this device, shown cliagram- 
matically in Figure 56, a double sheet-metal tank is employed, with the 
inner tank closed at the top by a screen and filter cloth. Liquid carbon 
dioxide is expanded directly into the inner tank or can which is usually 

16 Kuprianoff. J., "Ucbcr die Hersteltimg von fester Kohlensaure," Gcsellschaft fur Kaltewesen 
m.b.H.. Berlin (1931). 

"Martin, J. W., Jr., U. S. 1,659,431 (1928). 



1*08 



CARBON DIOXIDE 



maintained at pressures below 10 pounds per square inch gage. The car- 
bon dioxide snow resulting from this expansion is deposited below the 
screen while the evolved vapor passes through the screen, downwardly 
between the two shells and thence to the recompressor suction. Any one 
of the refrigerating cycles may be used in this process except the pressure 
snow-making cycle. 

The device, commonly known as a "snow tank," is mounted on a scale, 
upon which reliance is placed for an indication of when the tank has been 
rilled. A popular size has an interior tank capacity of 20 cubic feet and 
is filled to 500 pounds before opening. When the tank is filled it is dis- 
connected, and the snow shovelled into open molds where it is tamped by 




FIGURE 56. 

The Snow Tank. 



hand to secure approximately even distribution and pressed in open hydrau- 
lic presses at from 500 to 800 pounds per square inch pressure on the hori- 
zontal block faces. The optimum pressure is conditioned not only upon 
the mold wall friction and design but upon duration of pressure, density 
desired, moisture content and average crystal size of the solid carbon 
dioxide. Kuprianoff 18 has reported on laboratory experiments on snow 
pressing involving the relation of mold proportions to applied pressure and 
pressure duration. His results, however, do not consider varying particle 
size, nor varying moisture content, nor do they take account of variations 
in mold surface condition and frost-fouling which are unavoidable in prac- 
tice. As a consequence, optimum pressure time relationships in pressing 
are usually worked out by empirical experiment in individual plants. In 
view of the number of variables involved, it is natural that they are by no 

"Kuprianoff, J., Loc. cit. 



MANUFACTURE OF SOLID CARBON DIOXIDE 



209 



means uniform, but there is little difficulty in adjusting the density of the 
product in particular plants to the demands of their specific trade. Kupri- 
anoff's results are reproduced in Figure S7. 19 

The comparatively simple and crude snow tank method is still in use, 
and is much misunderstood. While it is ill-adapted for quantity produc- 
tion and involves from 3 per cent to over 10 per cent loss in transferring 



PRESSURE 
KG/CM* 



110 



II 



DENSITY 
K6/L 



1.6 




I.O 



1.6 
1.4 
1.2 
1.0 



1.4 
1.2 
1.0 



1.4 
1.2 

1.0 
0.9 



PRESS TIME s T 





1.0 
Ratio 



2.0 



3.0 



FIGURE 57. Relation Between Time, Pressure and Density of 
Solid Carbon Dioxide. (Data of Kuprianoff.) 

the snow to open molds for pressing, it was designed for the purpose of 
exploring a market at minimum capital investment. For that purpose it 
has not yet been surpassed in the art. 

Horizontal Presses. Following the snow tank, the earliest develop- 
ment in the direction of enclosed presses was the horizontal type press, 

** It is to be noted that Kuprianoff's test data are for cylindrical molds pressed from one end 
only, while American practice is all hut standardized on rectangular molds in which the design 
factor ///d=O.S (H is the height and d is the diameter of the block) but owing to compressing the 
block from both ends instead of only one, the effective equivalent of H/d becomes 0.25. 



210 



CARBON DIOXIDE 



known in the trade as the "Carbice" machine. 20 In this machine (Figure 
59 A) snow is deposited by expansion of liquefied carbon dioxide directly 
to pressures at or below its triple point in a conical enclosed hopper stationed 
above the press chamber. The snow is fed to the pressing chamber by 
means of a screw, or more often, by a series of rabble arms mounted on a 
vertical shaft. Pressing is from one end only, the plunger moving hori- 
zontally. The principal weakness of this machine is the difficulty of obtain- 
ing uniform density in the product, owing to the fact that the snow drop- 
ping into the chamber is somewhat more densely packed along the bottom 
of the press, producing finished blocks of less density at the top. 

This pressing difficulty is somewhat mitigated in the Solid Carbonic 
type of machine where the conical hopper and shaft are eliminated and 
the solid usually formed by evaporating the liquid directly in the press 
chamber. This produces a more uniformly distributed charge of solid 
prior to pressing. Employment of small hydraulic piston diameter, with 



i 



HTl 




FIGURE 58. An Early Horizontal Press known as the "Car- 
bice" Machine. 

an adequate supply of high pressure (2000 Ibs.) water, further gives 
extremely rapid pressing in this machine, the time per stroke not exceed- 
ing 3 seconds. It is believed that this rapid action violently "splashes" 
the solid in the chamber, thus redistributing it evenly across the transverse 
area and largely eliminating top to bottom density variations in the product. 

Since pressing takes place entirely from one end, however, there is 
naturally a longitudinal density difference, the portion of the block nearest 
the platen being somewhat more dense than the closure end. A precise 
statement of the amount of this variation is impossible because of the many 
variables which influence it, but it is eliminated in practice by removing 
the pressed block, turning it end for end, reinserting it in the press cham- 
ber and pressing a second time. 

In both of the above machines the length of the block is not susceptible 
to precise control, since the weight of the charge in the press chamber is 
regulated only by time. These difficulties are eliminated in a more elab- 
orate machine developed by the Dry Ice Corporation in 1928 and 1929, 

80 So called hccause developed by the Carbice Corporation, which at a later time became the 
Solid Carbonic Company, Ltd. 



MANUFACTURE OF SOLID CARBON DIOXIDE 



211 




Courtesy, Baldwin-Southwark Corporation. 

FIGURE 59. ("A" Left) An Early Horizontal Press and Snow Machine. 
("B" Right) A Vertical Press of Cast Iron Construction. One of the Early 
Presses of the Dry Ice Corporation. 




Courtesy, Baldwin-Southwark Corporation. 

FIGURE 59. ("C" Left) A Battery of Double Acting Piston Type Presses. 
Designed to Permit Low Construction. 

("D" Right) An Early Water-Operated Press of the Outside Fullback Type. 



212 



CARBON DIOXIDE 



shown in Figure 58. In this device snow is deposited in an upper cham- 
ber from which it is advanced by rabble arms into a space in which a tamp- 
ing device operates. The tamping operation distributes an even charge 
of snow in the pressing compartment of definite and adjustable size. The 
resulting snow is pressed from both ends and automatically discharged on 
a conveyor. When operated with snow of correct particle size, and at 
correct tamping and pressing rates, this machine turns out a product of 
exceptionally uniform density and size, and excellent storage and ship- 
ping characteristics. It has, however, been superseded in American prac- 
tice by one variation or another of the simpler and much less expensive 
vertical press and well over 90 per cent of current world production orig- 
inates in this type of press. 




Courtesy, Baldurin-Southwark Corporation. 

FIGURE 60. ("A" Left) Front View of a Modern Southwark Press with Press- 
ing Cylinders on the Side. 

("B" Right) Rear View Showing the Pipes and Oil Pump Arrangement. 

Vertical Presses. Figure 59 A, B, C, D, and Figure 60, illustrate 
some of the steps taken in press development in this country. It will 
be noted that the various modifications of this type of press are similar 
in their general features. All involve a central press chamber of rectan- 
gular form, the lower end of which is sealed by a hydraulically supported 



MANUFACTURE OF SOLID CARBON DIOXIDE 



213 



lower platen, except the Frick machine in which this arrangement is 
reversed by placing the chamber opening and its sealing platen on the top. 
Opposite the sealing platen, the chamber is equipped with a stuffing-box 
through which a piston or ram actuates the pressing platen. Details of the 




FIGURE 61. American Process for Making Solid Carbon Dioxide, 
Using a Frick Machine. 

stuffing-box construction and insulating methods in segregating the cold 
and warm portions of the press are of prime importance in determining 
smooth operation and low maintenance costs. / 

EUROPEAN SOLID-FORMING APPARATUS 

When it is considered that the bulk of United States production comes 
from a few plants of 40 to 250 tons daily capacity and that more than 
95 per cent of it is manufactured in plants with a daily carbon dioxide out- 
put of 10 tons or more, and that there is not today in the entire world, 
outside of the United States and England, a single plant of as much as 
10 tons daily solid carbon dioxide output, it is only natural that European 
solid forming equipment has evolved upon lines quite different from Ameri- 
can practice. 

The principal European methods developed are the Carba, Esslingen, 
Pegna, Agefko and Surth procedures, each claimed by a company of cor- 
responding name. 

The Carba Process. Of the above-mentioned processes the Carba is 
perhaps the best known, since it has been licensed to the firm of G. A. 
Schiitz, Germany's most widely represented exporter of carbon dioxide 
manufacturing machinery and since it is peculiarly suited to the conditions 
of severely limited demand and meager possible capital expenditures. 
Such conditions exist in many countries where the use of refrigeration in 
general and the consumption of ice cream in particular is not far advanced. 

The principal advantage claimed by the Carba company is the elimina- 
tion of the necessity of pressing the solid carbon dioxide. The elimination 



214 



CARBON DIOXIDE 



of hydraulic pump, operating valves and hydraulic cylinders, has served 
to reduce the capital required for small plants and has turned out a product 
which serves very well indeed for supply in countries where demand is 
small and intermittent, and where long-distance transportation or long- 
time storage do not enter into consideration. In the United States, on 
the contrary, it has been found that these advantages are not available, 
since no way has been found to make a product adapted to mass produc- 
tion methods and suitable for storage and transportation without introduc- 
ing the final step of pressing. 

A diagram of the Carba apparatus is shown in Figure 62, supplemented 
by an enlarged view of the nozzle upon which reliance is placed for the 
operation of the principle. Briefly stated, this principle is the impingement 
of a moist snow or slush of liquid and solid carbon dioxide against a mat 



, Liquid Inlet 




Expansion Nozzll 



FIGURE 62. 

Cross Section of the Prin- 
cipal Parts of the Carba 
Apparatus. 



/ O.ffustr 



of solid already formed. The compacting action arises from the inertia 
of the impinged slush and the creating of a pressure difference through 
the mass of porous solid by withdrawing carbon dioxide vapor down- 
wardly through the solid. 

In operating this device, its bottom closure is secured and liquid car- 
bon dioxide admitted through the nozzle situated in the upper portion of 
the apparatus and directed downward. It naturally requires a time inter- 
val before the pressure in the chamber is built up to the triple point, this 
time interval depending upon the rate at which vapor is being withdrawn 
during this initial stage. During this initial period, dry carbon dioxide 
snow is forced down against the screen by the vapor passing through it, 
building up a "filter mat" of dry snow in the bottom of the chamber. The 
quantity of such snow and hence the thickness of the dry snow layer may 
be nicely controlled by governing the time required to build up pressure 
to the triple point or the dry snow phase may be eliminated altogether by 
admitting vapor from elsewhere in the system to bring the device to the 
triple point pressure before liquid carbon dioxide is admitted. 



MANUFACTURE OF SOLID CARBON DIOXIDE 215 

Once the pressure in the device has been brought to or near the triple 
point, the special nozzle assumes its normal function, in which the Venturi 
action of the throat decreases the static head as the velocity head is built 
up in the narrower portions of the nozzle. 

The actual flow conditions in this tube, when it functions according to 
the patent claims, must be very complex, since all three phases are present 
and the material must partake at the same time of the flow characteristics 
of a sludge (liquid and solid) and of a foam (liquid and gas). It is said, 
however, that in passing through the nozzle some solid is formed as the 
static pressure momentarily falls below the triple point and that this is 
violently thrown or impinged downward with the remaining liquid in the 
form of damp snow. 

It will be observed that the behavior of the system is entirely dependent 
upon the relative magnitude of three flow rates : 

1. Rate of liquid admission. 

2. Rate of vapor withdrawal from the top of the apparatus. 

3. Rate of vapor withdrawal from below. 

If rate (2) becomes too great in relation to the other two, the pressure 
in the device will fall below the triple point and the apparatus will then 
function only as a snow tank. If rate (2) is cut to zero, withdrawing all 
the vapor from the bottom, the rate (3) will then be limited by the permea- 
bility and depth of the solid already formed, and unless the pressure is 
controlled by checking rate ( 1 ) the device will quickly rise above the triple 
point, after which the "damp snow" concept can no longer be operative. 
It will also be seen that when the rate (2) is adjusted to maintain effec- 
tively the desired pressure in the neighborhood of the triple point in the 
device, the nozzle dimensions being fixed, the moistness or "quality" of 
the snow will depend upon rate (1), which in practice is used to control 
this characteristic. It is said that maximum density of product is had when 
the percentage of liquid in the moist snow is thus regulated at 45 to 60 
per cent, although the method of determining this percentage has not been 
stated. The precise value is not susceptible to direct determination, and 
must be surmised from relative values of rate (1). That is to say, if we 
know when all other factors are equal, that a given value of rate ( 1 ) pro- 
duces dry snow and maintains a chamber pressure just below the triple 
point, while a second and higher value of rate (1) raises the pressure just 
above the triple point, and discharges only liquid into the chamber, it is 
presumed that a value of rate (1) midway between the two will deliver 
a mixture of 50 per cent liquid and 50 per cent solid. This method leaves 
much to be desired in rigidity, but no better one has apparently been 
advanced. 

In operation, when a charge of loosely compacted moist snow has 
accumulated, as judged by timing, rate (2) is reduced, establishing a higher 
pressure difference across the mass in the device by the continued with- 



216 



CARBON DIOXIDE 



drawal of vapor from below rate (3), and thus compressing the mass to 
increase its density, which may be raised as high as 1.5. 

Since the amount of vapor which can escape through the bottom screen 
is limited to that which can pass through the pores of the block and between 
the solid and the wall of the container, it necessarily follows that when 




FIGURE 63. The Carba Plant at Bern, Switzerland. 

a dense commercial product is made, most of the vapor must be taken 
out from the top, and only a minor proportion from below. This results 
in making the largest possible proportion of the vapor returned to the com- 
pressor system available at the highest possible pressure of solid formation 
(the triple point), which is very desirable from the viewpoint of power 
consumption. 



MANUFACTURE OF SOLID CARBON DIOXIDE 217 

The Carba snow-making device may be combined with any of the 
six type refrigerating cycles previously described, but the usual combina- 
tion is with the "pressure snow-making" cycle, sometimes supplemented 
by a second evaporator whose position in the cycle corresponds to that of 
the flash tank 12-13-16 in the "bleeder" cycle in Figure 53. This addi- 
tional flashing serves to somewhat simplify the operation by reducing the 
volume of top vapor which must be handled in the Carba device. 

The precise consideration of the thermodynamic efficiency of the Carba 
procedure depends upon the moistness of the snow deposit, and on the 
ratio of vapor returned at the triple point to vapor returned to the com- 
pressor system at or near atmospheric pressure. These quantities naturally 
vary somewhat with the regulation of the device, but efficiencies are very 
close to the values given for the "pressure snow-making" cycle in the usual 
operation. 

A typical installation of the Carba process appears in Figure 63, show- 
ing the generators of the Carba plant at Bern, Switzerland. In this case the 
generators are 180 mm. internal diameter and 1750 mm. long, 21 producing 
a "stick" of solid carbon dioxide weighing 60 kilograms, which is light 
enough to be removed by hand without special apparatus and cut into five 
cylindrical pieces of 12 kg. each. Five such generators are placed side 
by side and connected in parallel to liquid and gas manifolds. One gen- 
erator is filled with moist snow while the other four are undergoing the 
final stage of solidification during which vapor is removed from the bot- 
tom while the block is compacting and being reduced from 56 C. to 
78 C. This final solidification of the moist snow does not take place 
as rapidly as the first or filling stage, the filling requiring from 10 to 15 
minutes, while the final solidification requires 50 to 60 minutes. Hence, 
for steady operation five such generators are required to give a capacity 
of 150 kg. per hour, or six to give a capacity of 200 kg. per hour. Although 
these figures tend to emphasize the special fitness of the method for small 
hourly production when contrasted with vertical press capacities in Ameri- 
can practice commonly running twenty times the output per hour per 
machine, it must be noted in fairness to the Carba method that this time 
limitation is a question of depth of mass of solid rather than its transverse 
area. For this reason, were the process operated on the time cycle as 
given above, but employing the same horizontal section as the common 
American practice (20 in. by 20 in.), production of one half the Ameri- 
can figure per machine would be a reasonable expectation, provided the 
resulting 1300 pound "ingots" could be handled at a reasonable cost. An 
alternative is, of course, the increase of transverse area, with a reduction 
of height, accompanied by more frequent opening and closing of the device, 
but the use of the procedure without the added step of pressing has not 
yet been applied to mass production successfully. 

Figure 64 shows the schematic arrangement of the Carba apparatus. 

21 Salmony, A. t "Uber das Trockeneis," Verlag Ferdinand Enkc, Stuttgart (1933). 



218 



CARBON DIOXIDE 




FIGURE 64. Carba Process. 

The Linde-Surth Process. This process 22 involves a procedure quite 
similar to the Carba in that it also removes the evolved vapor downwardly 
through the bottom of the solid-forming container or generator. In this 
generator the freezing cell, which constitutes the solid-forming chamber, is 
connected to the outside insulated casing by means of a diaphragm. In 
operation the freezing cell is completely filled with liquid carbon dioxide 
from a supply tank situated above, which furnishes the liquid at a pressure 
of about 6 atmospheres and a temperature of about 53 C. A small part 
of the liquid in the freezing cell is permitted to expand through the porous 
diaphragm to the outside casing which is maintained at a pressure of about 
1 atmosphere by means of the suction of the gas compressor. The tem- 
perature lowering caused by this expansion lowers the temperature of the 
liquid within the cell below the critical point and solid carbon dioxide is 
formed. This expansion and freezing process continues until all of the 
carbon dioxide is in the solid state after which the block of dry ice is dis- 
charged through an opening in the bottom of the cell. 

Thje Agefko Process. 23 This likewise resembles the Carba process 
in claiming elimination of hydraulic presses, and in the use of a generator 
having a filter member at the bottom. In the Agefko procedure, the use 
of the Carba nozzle is foresworn, and the use of moist snow avoided by 
first injecting a charge of dry snow into the generator, and then admitting 
above it, preferably suddenly, liquid at 10 to 20 atmospheres, the higher 
value being apparently preferred. The relatively high pressure over the 
snow is said to compress it into a dense block, above which a charge of 
liquid is retained. Slight meltage along the walls affords an opening 
through which the liquid in this bath can penetrate downward, around, 
and into the compressed snow block, further increasing its density and 
welding it into a merchantable block. The bottom connection of the cham- 

German 581,727. 

German 599,367 and U. S. 1,925,041. 



MANUFACTURE OF SOLID CARBON DIOXIDE 219 

ber throughout the process is connected to the low pressure suction of the 
compressor system. 

The Esslingen Apparatus. This is an interesting device, in which 
the manufacturer has endeavored to solve the problem of solid carbon diox- 
ide manufacture for communities where the demand is too small to support 
a continuous operation, but where it is preferable to recover and purify 
carbon dioxide for 24 hours daily. This apparatus has as its essential 
feature one or more large vertical cylinders in which carbon dioxide snow 
is deposited as made, and where it remains hermetically sealed in storage 
until it is desired to press it into blocks. During this period, there is no 
loss of carbon dioxide except the leakage loss in the compressor system, 
and no cost of storage except the cost of the power required to compress 
the vapor evolved from the stored snow and the capital charges on the 
snow container, which are probably less in most cases than the capital 
charges on the extra capacity which would otherwise be required to make 
the product as required. 

The pressing equipment is of conventional type, except that it is 
mounted horizontally in a traveling crane, which may be moved by hand 
to bring it under any desired snow container for work. 

Blocks from 5 to 30 kilograms may be pressed, and machines are listed 
from 30 to 500 kilograms per hour capacity in steps of 50 kilograms. The 
size and capacity of the snow containers is varied to suit the individual 
plant conditions, but it is usual to provide sufficient capacity so that the 
carbon dioxide produced and converted to snow over 24 hours is pressed 
to blocks in one shift of 6 to 8 hours by a single man. 

The Pegna Apparatus. 24 This is another variation of snow pressing 
apparatus where the snow is filled into a chamber below the triple point 
and is especially intended for the convenient preparation and handling of 
smaller blocks, pressed to high densities. It consists of an inner cylinder 
surrounded by an insulating jacket. The inner cylinder is closed with 
a cover which is held in place by the three hand clamps. The lower part 
of the cylinder is closed with a hydraulic piston which serves to compress 
the snow to a block after formation. The liquid carbon dioxide enters 
the cylinder against a pressure of 2 to 3 kg. per sq. cm. which is main- 
tained in the snow chamber. The pressure inside is indicated by a gage. 
The carbon dioxide snow resulting from the expansion of the liquid forms 
a mat through which the gaseous carbon dioxide passes to a heat exchanger 
and thus back into the compression cycle again. A safety valve is pro- 
vided to protect the apparatus from excessive pressures and a valve in the 
base serves quickly to reduce the pressure in case of need. A hydraulic 
pressure of 180 kg. per sq. cm. is employed and the manufacturer lays 
special stress on the high density of solid carbon dioxide blocks obtainable 
with it. 

14 Pegna, E. G., Pergine Valdarno bei Arezzo, Italy, D. R. P. App. 46,630 (1930). 



220 . CARBON DIOXIDE 

N/ The Maiuri Process. 25 This method of producing solid carbon diox- 
ide is of considerable interest because of its similarity to the process ordi- 
narily employed for the production of water ice. The carbon dioxide is 
frozen in cans or molds from which the heat is removed by means of an 
alcohol bath cooled with ammonia refrigeration. The low temperature 
necessary, is produced with an ammonia absorption refrigerating machine 
operated in such a manner that a temperature somewhere between 60 
and -70 C. (-76 F. and -94 F.) is obtained. 

Figure 65 shows the essential parts of the apparatus used to carry out 
this process. Liquid ammonia collected in receiver G is expanded through 
the regulation valve / into evaporation coils in the freezing tank O. The 
freezing cans M, submerged in an alcohol bath, transfers the heat from the 




Holier, high pressure 

Boiler, medium pressure 

Condenser 

Absorber, medium pressure 

Rectifier for "A" 

Rectifier for "B" 

NII a Collector 

Absorber V.icuum 

NH a Regulator 

Water Regulator 

Heat Exchangers 

Freezing Molds for COo 

Frce/ing Tank 

Water Pump 



FIGURE 65. Maiuri Process for Solid Carbon Dioxide Manufacture. 

carbon dioxide to the ammonia evaporating coils. The temperature of the 
alcohol bath, in this apparatus, can be held between 55 and 62 C. 
The ammonia vapor from the expansion coils passes through a heat 
exchanger (not shown in the diagram) where it removes heat from the 
gaseous carbon dioxide passing to the freezing cans and thereby becomes 
superheated. The vacuum absorber // then absorbs the ammonia vapor in 
an ammonia water solution of about 4 per cent concentration and builds it 
up to about 13 per cent ammonia at the bottom of the absorber. The 
ammonia vapor pressure in the evaporating coils can be lowered to between 
2 and 3 Ibs. per sq. in. absolute, with a properly constructed absorber. 
The strong ammonia solution is then pumped through a heat exchanger 
to the first stage boiler B where the ammonia is driven off at a tempera- 
ture not exceeding 100 C. The vapor of ammonia from the boiler B is 

* Maiuri, G., Cold Storage and Produce Review, Sept. 21 (1933). 



MANUFACTURE OF SOLID CARBON DIOXIDE 



221 



passed through the rectifier F to the absorber D. In this absorber 
the ammonia is taken up in a weak ammoniacal liquor from the second stage 
high pressure boiler A and is built up to something like 34 per cent. In 
the second stage boiler A the temperature of the concentrated ammonia 
solution is increased to nearly 130 C. and the anhydrous ammonia thus 
obtained is collected in the condenser C from which it is sent to the freez- 
ing chamber again. 

The gaseous carbon dioxide is furnished to the freezing cans under a 
pressure somewhat above the triple pressure, usually from 80 to 100 Ibs. 
per sq. in. A heat exchanger cooled with the ammonia vapor from the 
expansion coils lowers the temperature of the incoming gas to approxi- 
mately 30 C. On entering the cans the gaseous carbon dioxide quickly 
condenses to a liquid and the drops of liquid fall to the bottom of the can 
and freezes to a hard compact mass. Freezing is allowed to continue until 



fry/Eg? 


/A V 


MA Y/ 

1 


f/n i. 

\ 


II ; 



Type 1 



Type 2 



Type 3 Type 4 

Types 1, 3, and 4 Standard Kefrfceratini? Cars with Extra Insulation Crosshatched. 

FIGITRK 66. Typical Arrangements of Dry Ice Transportation Cars. 

the cans are about half full, then the pressure is gradually lowered to atmos- 
pheric conditions and the blocks of solid carbon dioxide are removed from 
the bottom of the molds. 

The time necessary for the freezing to take place will vary, of course, 
with the design of the apparatus. According to the inventor a small plant 
produced 12 blocks of 11 pounds each in a period of 6 hours. The ratio 
of weight of steam used in thcgencrators to weight of solid carbon dioxide 
produced is said to be asjo^ras 1.7 to 1. The density of the solid obtained 
by this process is^bntit 1.48 or 92.35 Ibs. per cu. ft. 

TRANSPORTATION OF SOLID CARBON DIOXIDE 

The problem of selecting suitable size and construction for transporta- 
tion containers has already been briefly mentioned and some typical con- 
tainers illustrated (Fig. 49). However, the movement of large quantities 
of solid carbon dioxide from one place to another is becoming quite gen- 
eral in America and this phase of the problem will be considered more 
in detail. 



222 



CARBON DIOXIDE 



Car Transportation. Railroad cars of the refrigerator type are being 
used for the large scale transportation of solid carbon dioxide in ever 
increasing numbers. In some cases, these are ordinary standard refrigera- 
tor cars remodeled to fit the conditions encountered in moving this type 
of refrigerant, while in others special cars have been constructed for this 
purpose. The arrangement of four types of these cars are shown in Fig- 
ure 66. 

In arranging cars for transportation of solid carbon dioxide two factors 
must be considered ; first the proper insulation of the car body and second 
the proper sealing to prevent gas loss. The former simply follows general 
insulation practice, the insulating material being cork, some commercial 
refrigerator car insulant or occasionally Balsa wood. Insulation thickness 
ranges from 4 inches to 10 inches depending upon the type of service to 
which the car is to be put. Sealing to prevent gas leakage may be accom- 
plished by several methods but two of the most effective are the employ- 




FIGURE 67. Latest Type Ten-wheel Model AUTOCAR Truck for Long Dis- 
tance Transportation of Product. Dry Zero and Cork Insulation. 

ment of an all steel car shell, and the insertion inside the shell, but outside 
the special heat-insulating material, of a metal sheath of roofers' tin or sheet 
copper, with all seams locked and soldered. In the peak summer season 
standard refrigerator cars are often used for peak load requirements of 
short duration. In general, the "settled" loaded car loss averages 0.75 
per cent per day (loading and unloading excepted) for type 3, while type 1 
averages approximately 1 per cent and type 4 averages 1.25 per cent. 

Truck Transportation. Truck bodies designed for the transportation 
of solid carbon dioxide are insulated and sealed in much the same manner 
as railroad cars. Figure 67 shows a photograph of a new truck made espe- 
cially for the transportation of this refrigerant. 

Transportation Losses. A mathematically rigid treatment of the 
transit evaporation loss problem cannot be undertaken here with any hope 



MANUFACTURE OF SOLID CARBON DIOXIDE 



223 



of achieving practical significance because of the variation introduced in 
practice by evaporative cooling. There are, however, certain factors bear- 
ing on the problem which perhaps are worth discussing in some detail. 

Figure 68 represents a plot of solid carbon dioxide temperatures ver- 
sus the volume percentage of carbon dioxide in the air in equilibrium with 
it. This will be recognized at once as merely a form of vapor pressure 
curve, but it is immediately noted that reduction of the surrounding atmos- 
phere (i. e. the atmosphere at the evaporating face), for example, to 65 



FIGURE 68. 

Solid Carbon Dioxide Sub- 
limation Temperature versus 
Carbon Dioxide Content of 
Surrounding Atmosphere. 

(According to Plank 
and Kuprianoff) 




per cent, reduces the temperature of the carbon dioxide more than 5 C. by 
evaporative cooling. Figure 69 expresses the additional refrigerating effect 
of the remaining "supercooled" solid carbon dioxide in terms of per cent 
excess refrigeration capacity referred to the total cooling effect per pound 
of solid at 78.52 C. changing to a vapor at C. and atmospheric pres- 
sure, due to sensible heat removed from the remaining solid. 

When the block of solid carbon dioxide, made by whatever process, is 
first exposed to the air, whether for cutting, for wrapping, or merely for 
transfer from one vessel to another, evaporative cooling commences, and 



224 



CARBON DIOXIDE 



the block is chilled below its normal sublimation temperature in pure car- 
bon dioxide. The result is temporarily increased sublimation rate, with 
increased refrigeration available per pound of remaining refrigerant. Such 
decrease in temperature has the effect of discounting subsequent losses, for 
when the supercooled block is then placed in a car, truck, or shipping box, 




B.TU. Per Lb. 
'* * 




Per 6m 



FIGURE 69. Solid Carbon Dioxide Excess Refriger- 
ation Capacity Over Solid at 78.52 C. Versus Carbon 
Dioxide Content of Surrounding Atmosphere. 

(According to Maass and Barnes and Plank and 
Kuprianoff.) 

it finds itself protected from the air and surrounded by an atmosphere 
richer in carbon dioxide. If the sealing is good enough to maintain the 
carbon dioxide around the block at 100 per cent, the block will warm up 
again to 78.52 C. by absorption of heat before the evaporation loss in 
weight can approach a normal value calculated from the heat leakage of the 
box or other structure and the normal refrigerating effect of solid car- 
bon dioxide. 



MANUFACTURE OF SOLID CARBON DIOXIDE 225 

This discounting of loss will obviously vary with the time and nature 
of the air contacts and the purity of the carbon dioxide atmosphere main- 
tained in the container, and in practice it robs many loss test figures deter- 
mined under trade conditions of much of their significance, since it is not 
a constant factor and all the variables are rarely, if ever, known in com- 
mercial tests. In the trade, however, the phenomenon \vorks consistently 
for the customer and against the seller, since the seller must handle, and 
somtimes saw and wrap his product before weighing it for sale. During 
this period is it supercooling, and when sale is made by weight, the pur- 
chaser then receives a product of slightly more than normal refrigerating 
effect per pound. If he then places the block in a tight storage box, his 
loss will be somewhat reduced because discounted by the excessive loss pre- 
viously suffered. In practice this effect will amount to any value from 
none at all up to 4 per cent by weight of the solid made, depending on 
conditions of exposure. 

SEASON STORAGE OK SOLID CARHON DIOXIDE 

The problem involved in season storage of solid carbon dioxide can 
be best understood by considering that it has the general economic aspects 
of seasonal water ice storage, and the following additional features not 
encountered in water ice storage :- (} 

Economic Problems, fa) Although water ice plant capacity may be 
installed for as low as $1000 per daily ton of output, solid carbon dioxide 
plant capacity (for gas and solid) costs from $2000 to $15,000 per daily 
ton, depending upon the process used and its location. The capital charges 
on the idle peak load capacity are hence greater, and the incentive to use 
a moderate amount of storage capacity and limit the plant capacity is 
accordingly greater. 

(b) In specially favorable instances it is possible to place in storage 
solid carbon dioxide that has been manufactured from waste by-product 
gases, where no value is assigned to the gas employed because it would 
otherwise have no market. In this case the evaporation loss would be 
reduced to the cost of labor, power, \\ater and supplies used in the manu- 
facture of the evaporated material. In addition there should be added also 
the capital charges on a portion of the storage structure loaded with mate- 
rial not marketed, and the expense incurred for purification of unmarket- 
able product. Each of these values is, of course, peculiar to each specific 
plant location. 

(c) By all odds, the most difficult problem is involved in the com- 
parative newness of the industry, and the groat difficulty in forecasting 
markets accurately. Competitive plant capacity is likewise an important 
factor, and in seasons where the American enthusiasm for building new 
plants outruns demand by too wide a margin, all incentive to store is 
naturally removed. 

M For a typical analysis indicating the economic factors heating on season storage of manu- 
factured water ice, see Macintire, "Handbook of Mechanical Refrigeiation," page 427. 



226 CARBON DIOXIDE 

(d) In cases where by-product gas is used, and the seasonal demand 
fluctuation for the main product does not correspond to the seasonal 
demand curve for the by-product, season storage affords a logical means 
of bringing the variations into harmony. 

(e) The amount of season storage employed will determine to a con- 
siderable extent the economic significance of such storage. Thus, if only 
sufficient material is stored to care for peak load demands of the highest 
week's summer sales, it is apparent that the manufacturer preferring to 
construct additional plant capacity would have to assess the carrying charges 
on his additional plant for fifty-two weeks against one week's production. 
When it is considered that the capital cost of well-constructed season 
storage per ton of material available for sale has already been reduced to 
less than $30 in storages of 3000 tons net capacity, it is apparent that 
economic justification is merely a question of moderation in the use of 
storage and its limitation to a relatively small output in comparison to 
plant capacity. 

Trade Problems, (a) Since no economical, dependable mechanical 
refrigeration cycle is available for continuously maintaining temperatures 
below 78 C. in a large storage space, storage thus far constructed has 
relied upon the evaporation of a part of the stored material to preserve 
the remainder. This results in the rounding of blocks stored near the 
walls of the storage space. Such rounded blocks are entirely suitable for 
industrial applications, car refrigeration, and most types of motor truck 
refrigeration, but are not salable to the portion of the ice cream trade 
desiring to cut dry ice into cakes. Since railway and industrial outlets 
still take only a small tonnage in proportion to ice cream manufacturers 
and are not yet in a position to absorb sufficient off-size material, the con- 
struction of season storage from this point of view has been premature. 

(b) Changes in crystal structure taking place on long-time storage are 
not yet well understood. Indeed, the only adequate method yet known 
of determining whether or not a given product will stand long time storage 
is to store it and examine it afterward. It can be stated with assurance 
that the differences among the various patented manufacturing methods 
have less to do with such changes in storage than the character, amount and 
dispersion of traces of impurities. At all events, some of the material that 
has been stored has emerged in a very sugary condition, earning a bad 
reputation in the trade for itself, while other material has been held for 
periods as great as six months and sold to the most exacting trade without 
being distinguished from fresh product. Much work on the effect of 
traces of impurities on structure changes in storage remains to be done. 

Engineering Problems, (a) 1 It is imperative that the gaseous atmos- 
phere in season solid carbon dioxide storage be maintained as nearly stag- 
nant and as nearly of constant carbon dioxide content as possible, since 
changes of composition induce temperature variations due to evaporative 



MANUFACTURE OF SOLID CARBON DIOXIDE 227 

cooling, as has been discussed above. Such temperature variations cause 
evaporation of some parts of the charge and condensation of the carbon 
dioxide on material that has been supercooled by evaporation in a gas of 
lower purity. Because of this phenomenon, it is not uncommon to remove 
blocks from storage weighing as much as two pounds or 4 per cent heavier 
than when loaded into storage six months earlier. Such exchanges natu- 
rally render weight changes of individual blocks quite devoid of any value 
in indicating the merit of the storage as a whole. 

(b) Owing to the low temperature maintained, it would be very costly 
indeed to maintain a large storage space refrigerated throughout even when 
only a small proportion of its volume is occupied with stored material. 
This problem has been met by the use of a floating insulated roof, which 
is elevated once a year during the loading process, and lowered during 
unloading. The space above the floating roof is not refrigerated, and is 
in fact quite warm as a rule during the summer season, uncomfortably 
so at times. 

(c) In time the heat abstracted from surroundings will, of course, 
freeze the bearing soil under the structure. This must be provided for 
by mounting the storage on a suitably reinforced mat, preferably under- 
filled with gravel or porous filling, and provided with adequate drainage. 

(d) Opening the storage space for loading or unloading, even though 
complicated air-excluding devices are used, at best involves some loss of 
carbon dioxide and entrance of heat. This is minimized by mounting the 
floating roof (familiarly known as a "pancake") so that it may be rotated, 
and providing a loading slot through which the dry ice is handled. The 
exposure is thus limited to a narrow radial portion of the stored material 
where loading or unloading is actually in progress. 

(e) The importance of high carbon dioxide purity around the solid 
and minimum leakage through the structure, already pointed out, virtually 
necessitates a gas-tight shell, which has been cared for by employing only 
steel-shelled structures in which all joints have been electric welded and 
carefully tested for leakage. 

(f ) While many insulating materials might be applicable, it is desired 
to hold the movement of gases in the pores of the insulation to the lowest 
possible value, and vegetable cork is hence preferred, supplemented by 
aluminum foil covering to minimize possible convection at imperfect 
joints. 

Present Storage Structures. Up to the present time only two season 
storage structures have been erected. The first, illustrated in Figure 70, 
was built by the Drylce Corporation at its Elizabeth, New Jersey, plant. 
It is 47 feet internal diameter by 50 feet high, insulated with 12 inches of 
vegetable cork, and has a capacity of 3000 short tons of solid carbon 
dioxide, loaded in standard wrapped 10x10x10 in. cubes. 

The second, illustrated in Figure 71, was erected in 1931 at the Peoria, 
111., plant of Drylce Corporation of America, and is 40 feet in diameter, 



CARBON DIOXIDE 



FIGURE 70a. Storage Structure for Solid Carbon Dioxide at Elizabeth, N. J. 




FIGURE 70b. "Pancake" Floating Roof of Storage Structure at Elizabeth, N. J. 



MANUFACTURE OF SOLID CARBON DIOXIDE 



229 



75 feet high, with a capacity of 4000 short tons. At the present writing 
this structure has been filled only once. 

Evaporation losses in these structures on a daily basis are almost with- 
out meaning, largely because of the supercooling factor. The season losses 
on complete operation usually extending from early February to late 
August vary from 20 to 40 per cent, according to the loading and unloading 
times and rates. In all probability, figures below 20 per cent can be 
readily reached if trade conditions ever permit rapid and continuous load- 
ing late in the spring season, and complete unloading not later than July. 




FIGURE 71. Storage Structure for Solid Carbon Dioxide at 
Peoria, 111. 

It is as yet entirely too early in the development of the solid carbon 
dioxide industry to evaluate the commercial possibilities of season storage 
accurately, or to venture any prediction as to trends in design. The stor- 
ages described served to re-establish the confidence of the trade in the 
adequacy of peak season supply at a time when there was a shortage of 
plant capacity, but now seems quite likely to lie idle for so long as plant 
capacity continues in its present condition of unneeded excess. Perhaps 
the future trend will be determined by the seasonal characteristics of the 
markets developed for solid carbon dioxide as much as by any other factor. 



Chapter VIII 
Uses of Commercial Carbon Dioxide 

In discussing the uses to which carbon dioxide in any of its three 
phases, may be put, attention here will be directed principally to those uses 
which are or have been of some commercial importance. As with other 
industrial material, the commercial uses may be divided into three classes : 

1. Industrially important uses which absorb the bulk of the material 
produced, and which are economically feasible under the conditions 
of cost and volume of market existing. 

2. Proposed and tentative applications as well as minor uses, which 
because of cost, time required for development, small size of the 
consuming industry, or other limiting factors, are of small impor- 
tance at any given time, but may increase in volume when factors 
of price and service available permit expansion. - - 

3. Intermittent or obsolete uses in which the trend of the consuming 
industry has been away from the use of the product or towards 
a reduction of its consumption. 

It should be understood at the outset that the uses of commercial carbon 
dioxide clearly falling in the first class are limited to two ; the carbonation 
of beverages, which is largely accomplished by the use of the liquid form 
transported in steel cylinders and the refrigeration of ice cream, which 
naturally requires the solid form, more familiarly known as dry ;ce. 

Smaller markets have been developed in such promising fields as meat, 
fish, and frozen food refrigeration, charging compression refrigeration 
systems, mining coal, fire extinguishing, special low temperature operations 
and the packing of food products in inert atmospheres as well as larger 
volume applications in which the carbon dioxide is essentially an "inter- 
mediate" such as urea manufacture, but the existence of the carbon dioxide 
industry of today rests squarely upon the two applications first mentioned. 

In discussing the uses of carbon dioxide an attempt will be made to list 
the applications, as far as possible, under the general headings of solid, 
liquid and gas. To assist in visualizing the outlets for this product more 
clearly, a chart of use's 1 has been prepared and is given here as Table 69. 

>/ USES OF SOLID CARBON DIOXIDE 

Refrigeration. By far the most important industrial application of 
carbon dioxide is the direct use of the solidified product as a refrigerant. 

1 Jones, C. L., Chem. Met. Eng., 40, 76-9 (1933). 

230 



USES OF COMMERCIAL CARBON DIOXIDE 



231 



-iBN- 

m 





















' Afl 9-S 3 fc&g*! 2 - 

-IMM 




232 CARBON DIOXIDE 

The first suggestion of the possibility of commercial application of solid 
carbon dioxide appears to have been contained in the patent of Elworthy 2 
who says, "By the improved means of preparing and transporting solidified 
carbon dioxide this material will be rendered available for all or nearly all 
purposes for which ice is now used, as well as for any other purposes for 
which ice is unsuitable. By placing a small quantity of solidified gas in a 
small box, preferably made of silver or aluminum, and which box may 
also contain ether or alcohol, and immersing the box in any liquid or 
solution the latter may be cooled without contact with the gas, and in this 
way the delicate bouquet of wines and other liquors is preserved." 

Commercial application, however, did not immediately follow, and as 
a matter of fact, has not yet followed the lines of Elworthy's suggestion. 
The availability of water ice at low cost made it essential that solid 
carbon dioxide find collateral advantages to justify its higher cost. 

These were first found in the ice cream industry, where compactness, 
freedom from $lrip, ability to produce low enough temperatures, and lack of 
residue, combine to render solid carbon dioxide peculiarly suitable for the 
refrigeration of ice cream. 

Package Refrigeration. Solid carbon dioxide must be credited as the 
first means available to the ice cream manufacturer of refrigerating ice 
cream in throw-away paper containers. These are classified as "carry- 
home," "home-delivery" and "shipping" containers. "Carry-home" con- 
tainers are those refrigerated by the dispenser, and sold with sufficient 
dry ice to preserve the cream as a rule from four to eight hours. "Carry- 
home" package trade is naturally in small units, the one-quart size being 
most widely used. 

"Home-delivery" packages refer to those used for party and catering 
service, where the ice cream may be either in brick form or in molded fancy 
forms, and is provided with sufficient dry ice to hold until the expected time 
of consumption. Because of the character of service, the usual size pack- 
age is somewhat larger than in "carry-home" trade, ranging from two 
quarts to two gallons. For express and truck shipments to dispensers at 
some distance from the ice cream plant, cartons carrying two and one-half 
and five gallons of bulk ice cream in tin or paper cans are usual practice 
in the United States. 

The essential features of all such packages are : 

1. Sufficient dry ice for the desired time of transit. 

2. Insulation around the package as a whole. 

3. Insulation between the dry ice and the ice cream. 

4. Proper distribution of the refrigerating effect. 

It is obvious that when a small piece of solid carbon dioxide is brought 
into direct contact with ice cream, the cream in contact with the solid 
carbon dioxide will be over-refrigerated, while the remoter portions will 

Elworthy, H. S., U. S. 579,866 (1895). 



USES OF COMMERCIAL CARBON DIOXIDE 233 

be relatively warm. This tendency is obviously overcome by the use of 
sufficient insulation on the package as a whole, together with a proper 
degree of insulation between the solid carbon dioxide and the ice cream. 
In practice, the packages used are economic compromises in which some- 
what less than the ideal amount of insulation is used in order to reduce 
package cost, and skill in packing. The education of the consumer to 
temper the ice cream properly after delivery, is relied upon largely to 
overcome the usually faulty temperature distribution in the package. Pack- 
age design and practice varies so much with the time of year, climate and 
type of trade, that no single standard can be said to exist. However, the 
use of corrugated paper containers is common and Figure 72 shows the 




FIGURE 72. The Common Type of Ice Cream Package. 

ordinary package. Figure 73 shows the proportions commonly employed 
in making up such packages, although proportions are varied somewhat 
according to conditions by experienced packing crews in some of the more 
successful plants. 

Truck Refrigeration. Following the development of a market for solid 
carbon dioxide in refrigeration of packaged ice cream, its use for refrigera- 
tion of ice cream trucks next engaged wide attention, and is now in general 
use. 

The competitive standing of solid carbon dioxide as an ice cream 
truck refrigerant varies with the locality, since availability and low cost 
of solid carbon dioxide are important factors, and these are naturally at 
their best in the larger centers of population. 

Solid carbon dioxide has, however, firmly established its position as the 
lightest of all refrigeration methods permitting maximum pay load on 
a given chassis. Of all refrigeration methods, it has also established a 
position quite beyond question as the cheapest to install per gallon of truck 



234 CARBON DIOXIDE 

capacity, a factor of great importance in a seasonal business. It also 
possesses in the highest degree the factors of simplicity and dependability, 
sharing with water ice the familiar catch phrase : "A block of ice cannot 
get out of order." 




FIGURE 73. The Usual Method of Packing Ice Cream. 

Because of these advantages, solid carbon dioxide refrigeration is now 
accepted standard for ice cream truck refrigeration in the larger cities of 
the United States. Its application is extending to smaller centers more 
gradually as economical distribution of the necessary refrigerant to the 
more sparsely settled districts is developed. 

Figure 74 shows several types of truck refrigeration systems in success- 
ful use. Generally speaking, the simpler types have been found to suffice 
in this field, and the use of temperature control devices is not general. 
The proper proportioning of the equipment and proper hardening room 
and loading practice are usually sufficient to deliver the cream to the 
dispenser in a satisfactory condition. 

Ice Cream Dispensing Equipment. In dispensing of ice cream, solid 
carbon dioxide has made possible sweeping changes familiar to most 
residents of larger cities. The general characteristics of development in this 
market have been first, the necessity for limiting the use of solid carbon 
dioxide to very small and very efficiently insulated containers during the 
introductory period of small volume and high cost, and second a gradual 



USES OF COMMERCIAL CARBON DIOXIDE 



235 



shifting of the balance toward larger and less expensive types of dis- 
pensing containers as the cost of the refrigerant was lowered. 

Thus, the earliest type of dispensing was limited entirely to the retailing 
of ice cream novelties from vacuum jars. Initially only the one-gallon size 
was used, requiring approximately one pound of solid carbon dioxide daily 
for sufficient refrigeration. In this instance, a double-walled, wide-mouthed, 
silvered vacuum flask of Pyrex glass was employed, in which it was cus- 
tomary to have the residual gases between the walls largely carbon dioxide 
instead of air. 3 

The next step from the one-gallon container is the dispensing box or 
basket, carried over the arm. This type was originally developed for train 
and ferry-boat service, but has found application for roadside sale of ice 
cream novelties. 



FIGURE 74. 

Typical Truck Body 
Cooling Systems. 




TYPE 2 



Wvyy^XX/v/ft^^ 

fS_ -------- - ----- ----- - ^^ _ - ^- - __-.. f 



,0ry 



Ice 



Conductor Plate 



TYPE 3 



The next step upward in size leads to the ice cream dispensing cabinet. 
Here the problem becomes a little more complicated, inasmuch as solid 
carbon dioxide must meet the competition of other refrigeration methods 
which are much better adapted to dispensing cabinet use than to truck, 



3 Deuvil, C. O., Refrigerating Eng.f 20, 223 (1930). 



236 CARBON DIOXIDE 

package, or counter-dispenser design. It is further necessary that ice cream 
cabinets be satisfactory in most locations for the refrigeration of bulk ice 
cream, which means that the temperature must be controlled within a range 
corresponding to satisfactory dipping condition of the cream. A number of 
such cabinets have been introduced, and they are in successful use, although 
at this writing it is too early to state how far it may be possible for solid 
carbon dioxide cabinets to penetrate this important field. 

Of particular interest is a classification of the methods used for con- 
trolling temperature in the devices thus far -offered. It will be understood 
that it is general practice to insulate the solid carbon dioxide container 
sufficiently to prevent the temperature of the cabinet from going below the 
desired point, permitting a normal heat leakage through the insulation around 
the solid carbon dioxide bunker sufficient only to care for the minimum 
refrigeration demand, and conveying the variable portion of the heat load 
to the dry ice in one of the following ways : 

I. By fluid circulation. 

a. By thermal circulation of a liquid, usually acetone, metlianol or butanol, 
in a closed circuit, the flow being interrupted by a thermally operated 
valve. 

b. By thermal circulation of gas in a path controlled by therrnostatic means. 

1. The atmosphere in the refrigerated space is circulated, cooled by means 
of a surface, usually provided with fins, which is in turn cooled by 
solid carbon dioxide. 

2. The gas around the solid carbon dioxide is permitted to escape directly 
into the refrigerated space through a thermostatically operated valve, 
thus establishing gas circulation in direct contact with the solid carbon 
dioxide. 

II. By evaporation and condensation. 

In this method a secondary refrigerant is permitted to boil in an evaporator, 
and condensed in a condenser cooled directly by the solid carbon dioxide, the 
flow through the circuit and hence the temperature of the refrigerated space 
being controlled by any of the conventional types of valve used in the mechan- 
ical refrigeration art. The choice of refrigerants is naturally limited to those 
not frozen to a solid by the solid carbon dioxide. 

III. By variation in the thermal conductance of the paths of heat flow from the 
refrigerated space to the solid carbon dioxide. 

a. By wrapping the solid carbon dioxide. 

b. By placing the solid carbon dioxide on insulating pads, whose thickness 
and material are varied to produce the desired result. 

c. By varying the degree of contact between a cold surface directly refriger- 
ated by the solid carbon dioxide, and a second surface in heat-conducting 
relation to the space refrigerated. 

1. By thermostatically operated "make-and-brcak" solid contact. 

2. By thermostatically flooding and draining a gap between the two con- 
ductors, for example, with alcohol. 

IV. By interposing a layer of freezablc liquid between the refrigerant and the 
space refrigerated, such as an eutectic brine, the temperature being obtained 
by adjusting the melting point of the brine to the desired point. 

The commercial application of solid carbon dioxide to ice cream cabinets 
is as yet in its infancy, and it is quite impossible to say which of the above 
schemes will survive the test of time. Indeed, a number of the cabinets 
now in apparently satisfactory use can boast of no temperature control 



USES OF COMMERCIAL CARBON DIOXIDE 



237 



more advanced than wrapping the refrigerant in paper when the ice cream 
seems too hard. 

Refrigeration of Meat and Fish. While the development of this type 
of refrigeration has been somewhat slower than in the case of ice cream it 
has been found that express shipments of meat and fish can often be made 
cheaper when solid carbon dioxide is used for refrigerating instead of 
the less efficient water ice. Such shipments are usually made in containers 
such as are illustrated in Figure 75 and Figure 76. 



FIGURE 75. 

Packing Meat with Solid 
Carbon Dioxide for Refrig- 
erant. 




Both meat and fish are also transported in motor trucks employing solid 
carbon dioxide as the refrigerant, and the practice is a growing one among 
wholesale meat peddler trucks in the larger cities where solid carbon dioxide 
may be obtained cheaply and conveniently. The design of such trucks 
follows the same general lines as those employed in the ice cream industry. 

Railroad Transportation of Perishables. In 1924 the Canadian National 
Railways and the Dominion of Canada Bureau of Fisheries made an experi-' 
mental shipment of fresh fish from Halifax, N. S., to Montreal. A standard 
refrigerator car was used and the solid carbon dioxide, formed into 
cylindrical blocks and made by the expansion of liquid carbon dioxide from 



238 



CARBON DIOXIDE 



cylinders, was interspersed throughout the load. The fish arrived in 
Montreal in good condition, and the shipment received such favorable com- 
ment that it was freely prophesied that the time was not far distant before 
this new refrigerant would completely revolutionize the refrigerator car 
industry. 

During the spring of 1926 further experiments were conducted to 
determine the feasibility of refrigerating carload shipments with dry ice, 
in which fillets were shipped from the Atlantic seaboard to points in 




FIGURE 76. Fillets of Fish Refrigerated with Solid Carbon Dioxide. 

the middle west with varying amounts of dry ice placed directly in contact 
with the load in standard water ice refrigerator cars. 4 

v ' In 1929 the construction of refrigerator cars especially designed to 
utilize the properties of solid carbon dioxide was undertaken. The first 
cars so constructed, however, were not well enough regarded by their 
builders to have had their design details published in the literature. About 
a year later practical experiments were undertaken by modifying the con- 
struction of water ice refrigerator cars and testing their actual performance 
in a constant temperature room, with a view to evolving a workable con- 
struction for a dry ice refrigerated car. 5 In Figure 77 is shown diagram- 
matically the arrangement of refrigerant, air flow, and thermostatic control 

4 Martin, J. W. f Jr., Railway Age, 85, 1239-41 (1928). 
Jones, C. L., Railway Age, 90, 363 (1931). 



USES OF COMMERCIAL CARBON DIOXIDE 



239 



in a resulting car. Such cars are in service in parts of the United States, and 
have transported successfully more than 100 carloads of dressed hogs and 
pork products, many shipments of fresh eggs, and numerous carloads 
of frozen foods. King has described such cars and outlined the results of 
their operation. 

Solid carbon dioxide has also been applied to the refrigeration of 
carload shipments as a supplement to the customary refrigeration with 
water ice. When so used it is commonly referred to as a "booster" or 
"auxiliary" refrigerant. The factors involved in this use, with particular 
reference to the shipments of fruits and vegetables, have been investigated 
by Brooks and his associates 7 who found that the gas evolved by 300 to 



_H EL. 



Air Flow 



Dry \cm 




Ceiling Duct 



Thcrmoatotic Damper 



Bunker Insulation 



FIGURE 77. Controlled Refrigeration of a Refrigerator Car with Solid 
Carbon Dioxide. 

1000 pounds of solid carbon dioxide placed above loads of strawberries, 
peaches, and dewberries is usually as effective as 21 F. lower temperature 
during the first 36 hours in prolonging the life of the produce. This type 
of application has also been used in the shipment of meats, in which it is 
customary to hang from 50 to 300 pounds of solid carbon dioxide from 
the ceiling of a refrigerator car cooled by the ordinary ice and salt practice. 
The reduction of temperatures by such a small amount of added refrigera- 
tion is not impressive, but owing to slightly lower humidity or to the effect 
of carbon dioxide on the meat, the practice is reported to result in better 
appearance of the delivered product. 

Some study has also been given to the use of solid carbon dioxide as a 
refrigerant in cooling smaller unit containers for rail shipments. Church 8 
has described such a unit container cooled by means of a metal bunker 
having an extended or finned cooling surface. 

King. C. W., Ice and Refrigeration, 84, 343-6 (1933). 

T Brooks, Charles. Miller, E. V., Bratley. C. O., Cooley, J. S., Mook, Paul V. ( and Johnson, 
H. B., "Effect of Solid and Gaseous Carbon Dioxide Upon Transit Diseases of Certain Fruits and 
Vegetables," U. S. Dept. Agr., Tech Bull., 318, 1-59 (1932). 

"Church, Refrigerating Eng. t 23, 33 (1932). 



240 CARBON DIOXIDE 

Cooling and Freezing Uses. In the preceding discussion emphasis 
was placed on the application of solid carbon dioxide for holding material, 
chiefly foodstuff, at a reduced temperature to prevent spoilage. It is now 
well to consider another field in which the refrigerating effect of solid car- 
bon dioxide is used to produce low temperatures or to extract heat from 
certain substances in order to freeze them. 

Shrinkage of Mac/line Parts. One of the most interesting uses of solid 
carbon dioxide in this field is the cold shrinking of machine parts, both as a 
substitute for the older brine-shrinking method, and to take the place of 
press fits. The study of the use of liquid air for shrink fitting 9 naturally 
led to focussing attention on the possibility of shrink fitting with the cheaper 
and more available, though less frigid, solid carbon dioxide. 

Among the first such uses was the insertion of bronze liners into the 
cylinders of hydraulic machinery, where it has been found sufficient to 
pack the interior of the liner with crushed solid carbon dioxide. Care is 
taken to make the insertion rapidly to avoid loss of temperature gradient, 
and it is usual to slush the outer surface of the liner with kerosene or alcohol 
to avoid the formation of frost from atmospheric condensation. It is said 
that slightly higher shrinkage allowances than with ice and salt cooling 
have been used with success. 

A somewhat more elaborate arrangement is employed in shrinking cast- 
iron cylinder liners into engine blocks, shown in Figure 78. 10 In this 
instance the cylindrical liner is placed on an aluminum spindle cooled by 
conduction to a block of solid carbon dioxide in a rotary cooling cabinet. 
Rotation of the cooling element by means of a pedal serves to bring a 
fresh liner in position for removal, and it is found that twenty minutes in 
the cabinet suffices to chill the liners to approximately 65 C. At this 
temperature they may be inserted into the cylinder block by hand, replacing 
a press-fitting operation, with the elimination of a press and some saving 
in time since it is not necessary to position the cylinder block accurately to 
insert the liners. 

A very similar arrangement has been used for the production chilling 
of heat-resistant alloy valve seat rings in automotive engines. In this 
instance, however, the rings feed by gravity through a chilliag chamber 
cooled by solid carbon dioxide, emerging at a temperature permitting them 
to be dropped into their places in the engine block without further treatment. 
Still other special shrinking operations have been performed by immersing 
the parts directly into, a freezing mixture of solid carbon dioxide with 
kerosene or methanol. 

Generally speaking, it is found possible to obtain shrink fits approxi- 
mating 0.1 per cent of the linear dimensions of the shrunk part in working 
with steel. The coefficient of expansion of the metal in question and the 
shape and size of the parts as well as the temperature of the warm part 

David, E. V., and Farr, W. S., Power, 74, 506 (1931). 
10 Herb, C. O., Machinery, 39, 305 (1933). 



USES OF COMMERCIAL CARBON DIOXIDE 241 

must be taken into consideration. The method is too young as yet to 
appraise its full possibilities in the metal working industries, but has already 
achieved recognition as the cheapest and most convenient method of 
accomplishing certain assembly operations. 

Chilling Aluminum Alloy Rivets. It is well known that the rate at 
which the so-called air hardening alloys of aluminum age is a function 




FIGURE 78. Rotary Cooling Cabinet for Cooling Cylinder 
Liners for Engine Blocks, Refrigerated with Solid Carbon 
Dioxide. 

of temperature. Unfortunately, some of the strongest alloys age so rap- 
idly at room temperatures that rivets made from them quickly become 
unworkable, requiring either that they be re-annealed just before they are 
to be driven, or that the aging phenomenon be retarded. 

It has been customary for some time to retard the hardening of such 
rivets by refrigeration using water ice, but solid carbon dioxide offered 
the advantages of adaptability to small unit chilling boxes in which a local 



242 



CARBON DIOXIDE 



supply of soft rivets could be maintained at each working position in an 
aluminum fabricating shop. Solid carbon dioxide is now the accepted 
and all but universally used refrigerant for storing such rivets in airplane 
construction shops. 11 Figure 79 illustrates a Balsa wood box of the type 
commonly used at each work place to hold a supply of soft aluminum alloy 
rivets. 

Cold Treatment of Special Steel Luerssen and Greene 12 have investi- 
gated the properties of certain silicon steels which are hardened by chilling 
to subzero temperatures by means of solid carbon dioxide. The method is 




FIGURE 79. Balsa Wood Container for Refrigerating Aluminum Alloy 
Rivets with Solid Carbon Dioxide. 

not yet applied commercially, but offers interesting advantages arising from 
the fact that parts may be machined and then hardened cold with com- 
plete freedom from any question of warpage or oxidation. 

Laboratory Uses. Solid carbon dioxide finds many uses as a low 
temperature refrigerant in laboratory work. Killeffer 13 has pointed out 
its adaptability to the dehydration of organic solvents, and states that 
ether may be dehydrated by freezing out moisture with solid carbon dioxide 
rapidly and economically. 

It is convenient in controlling the consistency of sticky and gummy 
materials for sampling and grinding. Thus, rubber samples may be packed 

Refrigerating Eng., 22, 182 (1931); Iron Age, 78, 337 (1932); Metals and Alloys, 2, 165 (1931). 
"Luersscn. G. V., and Greene, O. V., Trans. Am. Soc. Steel Treating, 501-52 (1932). 
M Killeffer, D. H., Ind. Eng. Chem., Anal. Ed. t 3, 386-7 (1931). 



USES OF COMMERCIAL CARBON DIOXIDE 



243 



with crushed solid carbon dioxide and ground in a chilled mortar, facili- 
tating solution of the ground sample, and simplifying its handling. Similar 
advantages attach to the grinding of other gummy or plastic materials, as 
it will be found that few substances exhibiting such properties at room tem- 
perature fail to become quite brittle when chilled to the temperature of 
solid carbon dioxide. 

The fact that vapor evolved from evaporating solid carbon dioxide 
is extremely dry, its dew point being at most the sublimation tempera- 
ture of the solid carbon dioxide, leads to drying applications where oxida- 
tion is regarded as undesirable. Thus, biological serums are occasionally 
concentrated by low temperature evaporation in this manner. 

Freezing of sections for histological work has long been accomplished 
by means of solid carbon dioxide. Dunn 14 has described a convenient appa- 
ratus especially designed for this purpose which is illustrated in Figure 80. 



held against 
Dry Ice 




M" thick Copper 
Disc for Tissue 



Bakeltte Handle 
%" diam. 



FIGURE 80. Microtome Attachment for Freezing Sections of Tissues with Dry Ice. 

Solid carbon dioxide is also useful in the laboratory for low temperature 
tests of the properties of materials. Thus, many laboratories use it in 
making cold tests of lubricating oils, and it has been employed to cool 
special test spaces in the investigation of gasoline engine performance at 
low temperatures, the study of the behavior of building and especially 
roofing materials at low temperatures, and in perfecting the design of a 
cold weather windshield-wiping device. 

Many of these laboratory applications have their counterparts on a 
little larger scale in industry. Thus, the cooling of vacuum traps for the 
protection of laboratory vacuum pumps from volatile materials find a direct 
parallel in the cooling of similar traps in the manufacture and repair of 
neon and other gas-filled tubular signs. Indeed, the sign industry probably 
employs the cheaper and more available solid carbon dioxide today on a 
wider scale than the liquid air formerly used for the purpose. 

"Dunn, F. L., 7. Lab. CKn. Med. t 16, 627 (1931). 



244 CARBON DIOXIDE 

Likewise the laboratory application in chilling rubber and gummy 
materials for grinding finds a parallel in the grinding of aniline dyes, in 
which some operators prefer grinding of solid carbon dioxide in small 
amounts directly with the dyestuff to other methods of cooling. This refrig- 
erant ground with the dye is obviously applied in the most efficient manner, 
since the refrigeration is applied directly inside the mill. It seems possible 
that the gas evolved may help prevent "balling" and "gumming" in the mill 
by aerating the product and providing for rapid adsorption of a gas film 
on freshly formed surfaces. 

Freezing to Stop Floiv. There is occasional use of small quantities of 
solid carbon dioxide for freezing off flow in pipes where other shut-off 
facilities are not available and it is necessary to make repairs. 15 This 
method probably has a wider usefulness than has yet appeared, since solid 
carbon dioxide has not always been available when emergencies occurred, 
and it has hence not been used in many instances where it might have been 
helpful. At least one case is on record, however, of a water main being 
shut off by filling a trench around a section with solid carbon dioxide. 
Such use of any refrigerant naturally presumes a speed of freezing suffi- 
cient to freeze the material through to the center of the pipe, involving not 
only the question of diameter, thickness, and material of which the pipe 
is made, but the latent heat of fusion of the liquid in the pipe, and its 
temperature, heat capacity and rate of flow past the point which is to be 
frozen off. 

A similar case of emergency freezing is to be found in the disposal 
of dangerous materials under pressure in leaky or dangerous containers. 
Thus, a case has been recorded in which it was necessary to dispose of a ton 
container of chlorine the valve of which had become badly corroded and had 
commenced to leak. It was considered dangerous to tamper with the valve, 
or to move the container, which was in a congested area. Solid carbon 
dioxide was packed around the container until the vapor pressure of the 
chlorine was reduced below atmospheric pressure, as judged by the fact 
that the leak ceased to exhaust chlorine, and commenced to draw in air. 
It was then found easy and safe to replace the defective valve. 10 

Of somewhat similar character is the discovery that when chlorpicrin 
is mixed with solid carbon dioxide, its vapor pressure is reduced to such a 
low value that the mixture may be handled in open buckets without the 
necessity of the operator wearing a gas mask. The application of this 
fact to the use of chlorpicrin in fumigation is obvious, although the use to 
date has been very limited. The possible application of the same phe- 
nomenon to the safe transportation of noxious materials in large quantities 
during war time is of the greatest importance, holding out the possibility 
of large savings in the decreased number of pressure containers required, 
and reducing the use of approved pressure containers possibly to the handling 

Laughton, W. M., Chcm. Met. E* ff ., 37, 643 (1930). 
"Anon., Ind. Eng. Chcm., News Ed., 9, 197 (1931). 



USES OF COMMERCIAL CARBON DIOXIDE 



245 



of small unit quantities at the scene of action. It would thus be possible 
to effect bulk shipments from the manufacturing plants to the filling sta- 
tions near the arena of war in open insulated boxes, reliquefying the 
products at the filling station and separating the carbon dioxide, in order 
to fill the noxious material into approved pressure containers for further 
shipment to the front in smaller unit shipments. Composite products made 
up of solid carbon dioxide mixed with volatile noxious organic materials 
have been made on a small scale and the practicability of their safe trans- 
portation in insulated sheet-metal boxes has been established, but there is 
no present commercial demand justifying wide use of this method of 
transportation. 




FIGURE 81. Cabinet for Hardening Fancy Forms of Ice Cream, Refrigerated 
with Dry Ice. 

Chilling Golf Balls. Solid carbon dioxide has been applied to refrigera- 
tion in the manufacture of golf balls in two ways. The centers have been 
chilled prior to winding, not only insuring that they hold their shape during 
the winding operation, but no doubt causing a little added tension by reason 
of the later expansion as the center warms up. It has also been the practice 
in at least one plant to chill the finished balls with solid carbon dioxide 
rendering any scarf at the junction of the mold sufficiently brittle to be 
readily removed by merely breaking off. 

Somewhat similar to this use is the chilling of crepe rubber for trim- 
ming to size. In this case trouble previously experienced in trimming crepe 
rubber, for sound-proofing airplane cabins, accurately to size was eliminated 
by chilling the sheets to brittleness between metal sheets refrigerated with 
solid carbon dioxide, then cutting to size when the chilled rubber sheet had 
warmed up approximately to the cutting consistency of pasteboard. 



246 CARBON DIOXIDE 

Freezing Food Products. It is sometimes found desirable to use solid 
carbon dioxide for freezing food products in cases where the convenience 
of the refrigerant outweighs the disadvantage of cost. Pedlers sometimes 
operate devices mounted on trucks for freezing custard or ice cream. 
Also manufacturers often use this refrigerant to harden "fancy forms" 
of ice cream in cupboards such as that illustrated in Figure 81. 17 

For small scale experimental freezing, several devices employing solid 
carbon dioxide have been used. Burke 18 has offered a small unit for such 
work, in which motor-driven agitation of a brine bath cooled with solid 
carbon dioxide affords apparatus for laboratory freezing operations under 
close thermostatic control. Similar and quite as efficient is the laboratory 
type cooler developed by Dry Ice Corporation. 19 A somewhat different 
construction has been employed by the Georgia Experiment Station. 20 
Goosmann 21 has proposed the freezing of food products by direct contact 
with liquefied carbon dioxide at low temperatures, and it would seem that 
if suitable apparatus is developed, this method should possess advantages 
in its great speed, its freedom from oxidizing influences, its complete 
freedom from deformation of products, and its indifference to shape and 
size. 

Producing Liquid Carbon Dioxide. While most of the solid carbon 
dioxide is employed for its refrigerating properties, some is also used for 
its carbon dioxide content. The great difference in soiling price between 
solid and liquid carbon dioxide is responsible for the development of 
evaporators or converters for the conversion of the former into the latter 
state. This conversion may be accomplished in evaporators designed for 
employing the refrigerating effect of the solid and then making use of the 
resulting gas or it may take place in a simple container in which solid 
carbon dioxide is placed and the gas taken from the top after liquefaction 
has resulted from the transfer of heat from the surrounding atmosphere. 
Because of its simplicity and the fact that the gas and refrigeration are not 
always needed at the same point the tendency at present seems to be 
towards the simple evaporator. 

In liquefying solid carbon dioxide the fact should be kept in mind 
that for equal weights, liquid carbon dioxide requires more space than the 
solid. While the solid at 75 C. occupies a volume of 0.0105 cubic feet 
per pound (theoretical cf. Table 82) the liquid requires almost twice that 
volume or 0.01689 cubic feet at 25 C. Even with the less dense com- 
mercial solid carbon dioxide the change will be practically of the same 
order. Liquefiers must therefore be designed to withstand the extremely 
high pressures which will result if they are to be completely filled with 

"Houlton, B. F., Ice Cream Trade /., 27, 56 (1931). 

"Anon., Ice and Refrigeration. 79, 219 (1930). 

U. S. Patent 1,873,130 (1932). 

80 Woodroof, J. G., Ga. E*p. Sta. Bull.. 163, (1930). 

n Goosmann, J. C., Ice and Refrigeration, 81, 56 (1931). 



USES OF COMMERCIAL CARBON DIOXIDE 



247 



the solid. It is better, however, to charge the liquefiers with only sufficient 
solid to permit expansion on melting. 

Figure 82 shows diagrammatically two forms of liquefiers according to 
Goosmann. 22 

Solid Carbon Dioxide for Rain Making. The distribution of finely 
divided solid carbon dioxide has been proposed as a means of assuring 
fair weather for important events on foggy or misty days by promoting 



FIGURE 82. 

Solid Carbon Dioxide 
Liquefiers. 

Unit at left having suffi- 
cient space to allow for the 
expansion of the solid on 
melting. 

Unit at right provided with 
condensing coil below the 
solid. 




Li quid Receive! 



precipitation over a small area. For this purpose a trial was conducted 
in Holland in 1930 in which three aeroplanes were employed to distribute 
powdered solid carbon dioxide over the clouds. The results 23 are said to 
have shown promise, and there is no question that sufficient quantities of 
solid carbon dioxide used in this manner will cause precipitation, but suffi- 
cient detail is not furnished on the results obtained from the trial to sup- 
port any judgment as to the possible practical significance of the method. 

"Goosmann, J. C., Ice and Refrigeration, 79, 134 (1930). 
83 Ice and Refrigeration, 79, (1930). 



248 CARBON DIOXIDE 

USES OF LIQUID CARBON DIOXIDE 

In Mechanical Refrigeration. The oldest use for carbon dioxide in 
the refrigeration field is in the recharging of compression refrigerating 
systems employing carhon dioxide as the refrigerant. Inasmuch as the 
thermal properties of carbon dioxide utilized in such machines have been 
reviewed in preceding chapters, and the literature of compression carbon 
dioxide refrigeration deals largely with mechanical detail, it will suffice 
here to refer to more comprehensive works on mechanical refrigeration. 24 

Due to the fact that the critical temperature of carbon dioxide is very 
near ordinary room temperature it has not received much favor as a 
refrigerant where condenser water temperatures are high, but in climates 
where cool water is available, and more particularly in places where safety 
has been highly regarded, the carbon dioxide machine has had wide recogni- 
tion. These refrigerating systems probably exceed in number all other 
types in marine work, where dependability and freedom from hazard to 
operators in case of leakage or loss of charge are essential. In theater 
cooling many carlxm dioxide machines are in service, presenting the 
advantage that leakage into the air of the ventilating system, should it 
occur, could occasion no panic and in all probability would not even attract 
the notice of the patrons. For similar reasons many carbon dioxide systems 
are found in hospitals and other public places. 

The use of liquid carbon dioxide here is confined to providing the 
original charge for the system, and making up losses by leakage from time 
to time. The principal requirements are that the substance must be as 
pure as possible, present commercial products for the purpose analyzing 
over 99.7 per cent carbon dioxide, and that it must be dry, since moisture 
in the system occasions difficulty with expansion valves, and tends to 
accumulate in the evaporator, where it naturally interferes with both flow 
and heat transfer if sufficient quantities accumulate. 

The Cardox Blasting Device. This is a device in which the expansive 
force of liquid carbon dioxide is used for blasting down coal. The process 
has many advantages over ordinary explosives and is rapidly taking its 
place as an essential to the coal mining industry. 

The Cardox cartridge, shown in Figure 83, is an alloy steel tube closed 
by caps on either end, which is filled with liquid carbon dioxide, which at 
the proper time is vaporized by the application of heat, the force being 
allowed to escape at a predetermined pressure by the shearing of a mild 
steel disc. Heat is applied to vaporize the liquid carbon dioxide from 
within the cartridge through the combustion of a mixture of chemicals in 
a paper tube known as a heater. The heater is a paper tube averaging 15 
inches in length and g- inch in diameter. One end of this tube is closed 
with a wood plug through the center of which projects the positive terminal 

"Pratt, J. II.. Ice and Refrigeration, 65, 141 (1923); Macintire, H. J., "Handbook of Mechanical 
Refrigeration," John Wiley and Sons, New York (1928). 



USES OF COMMERCIAL CARBON DIOXIDE 



249 




> I- 

g H* 

.,$ u -j J 

n^ 

So a e * * 



!?)' 



! I S S 



10 ID D 
X X X X X X 



o 



u 

ff 




250 CARBON DIOXIDE 

wire of an electric match. The negative terminal wire comes out under 
the shoulder of the plug. When the heater is placed inside the cartridge 
the negative terminal wire makes a ground contact against the inner wall 
of the steel cartridge while the positive terminal wire is engaged by an 
insulated electrode in the terminal cap. The heater tube contains, besides 
the match, a powder mixture known as the heating compound. This com- 
pound comprises an intimate mixture of potassium perchlorate, aluminum 
and carbon, so balanced as to provide an excess of oxygen in the reaction. 
The reaction is started by ignition of the match by an external source of 
electric energy. The thermal value of this compound is about 1600 calories 
per gram of mixture. 

The temperature of the gases in the cartridge just before the discharge 
is approximately 350 C., which is safely below the ignition temperature 
of any mixture of natural gas, coal dust and air. Upon release, the 
expansion has a natural refrigerating action so that the final temperature 
of the released gases at atmospheric pressure is lower than the normal mine 
temperature. The air in a room that has just been shot with Cardox is 
perceptibly cooler after the shots are fired. 

The pressures at which the shearing discs fail vary with the diameter 
of the orifice and the thickness of the discs and are maintained between 
a minimum of 10,000 pounds and a maximum of 30,000 pounds per 1 square 
inch. 

The cartridges have screwed caps at each end, one of which confines and 
holds the shearing disc while the other contains the filling valve and the 
electric contacts. After the discharge the cartridges are recovered from 
the coal and returned to a charging plant located usually at the mine, 
where the charge and disc are renewed for the next service. These 
cartridges are used daily over a period of years, requiring only a few 
minutes each for renewal of the charge. They are safe to handle and to 
transport and cannot be discharged except by application of an electric 
current through properly insulated contacts. They are of various sizes, 
ranging from If inches to 2 T ^ inches in diameter and from 20 inches to 
47 inches in length. The weight varies from 9 pounds to 35 pounds, accord- 
ing to size. Their use in the drill hole at the face of coal is similar to that 
of explosives. They are inserted in the drill hole, tamped in place, con- 
nected to the usual shotfiring cable and discharged by a pocket type blasting 
generator or a dry cell battery. After having been discharged the cartridges 
are returned to a charging plant where the caps are removed and a new disc 
and heater inserted and the caps replaced. The cartridge is then placed 
in a charging clamp and by operation of a packed wrench the filling valve 
is loosened. Liquid carbon dioxide is allowed to flow through this valve 
until the cartridge is filled, after which the valve is reseated and the 
cartridge is removed from the clamp. The weight is checked and the 
electric circuit is tested. Then the cartridge is ready to be returned for its 
next service at the face. Carbon dioxide is drawn from standard shipping 



USES OF COMMERCIAL CARBON DIOXIDE 



251 



cylinders and delivered in liquid form at about 30 F. to the charging 
clamp (Fig. 84). For this service a standard type of carbon dioxide 
refrigeration plant is used, which has a capacity of f ton of ice in 24 hours. 
A S-horsepower motor and a single-stage compressor are used with double 
pipe coolers and condensers and a liquid receiver having about 3 cubic 
feet capacity. 

Cardox costs somewhat more than black powder or permissible explo- 
sives. There must therefore be other attendant advantages to justify its 
use. The safety of Cardox permits the convenience of its use during the 




Courtesy, Safety Mining Company. 

FIGURE 84. A Charging 1 Plant at a West Virginia Mine where Cardox Cartridges 
are filled with Liquid Carbon Dioxide. 

worldng shift. A more tangible advantage is an increase in the per- 
cent^ge of coarse sizes of coal in the mine-run product. 
y Coal prepared with Cardox is said to be stronger in structure and does 
not break up so much during shipment as that blasted with permissible 
explosives. 

Thus far it has not been possible for these advantages to be made avail- 
able without an increase in the operating costs; hence all factors are 
analyzed as thoroughly as possible in the case of each individual mine 
before the system is installed and new installations are made on a trial 
basis until the various factors are established and evaluated. 

Some of the large mines in Franklin County, Illinois, are using the 
Cardox method of mining. Since these mines are only a few miles apart 



252 CARBON DIOXIDE 

and are connected with good roads, a central charging station has been 
established from which the mines are served, the loaded cartridges being 
delivered daily to the mines and returned to the central plant for recharging. 

In the State of Utah it happens that there is a well which produces 
carbon dioxide in such quantities and at such a pressure that it is possible 
to fill these cartridges without refrigeration or compressing equipment. 
Despite this advantage, however, the present practice is to ship the liquefied 
gas to the mines and fill the cartridges as already described. 

The Cardox method is being extended rapidly in Great Britain and 
tests are now under way leading to prospective development in France 
and Canada. 

Liquid Carbon Dioxide as a Power Producer. The history of carbon 
dioxide is filled with references to its use as a power generator for operat- 
ing various mechanical devices. Among these applications one finds 
reference to its use as a motive power for operating flying machines, 25 for 
propelling torpedoes, 20 the elevation of ladders on hook-and-laddcr fire 
trucks, 27 and many others. 

Operation of Bell Buoys. Liquid carbon dioxide is also used as a con- 
venient and reliable decentralized source of power in the operation of bell 
buoys. The buoy at the entrance of Chesapeake Bay is operated from a 
cylinder containing 100 pounds of liquefied carbon dioxide, which filters 
from the cylinder through an asbestos-packed check valve until 19 atmos- 
pheres pressure is built up in a chamber, when it is released to operate a 
bell striker. Sufficient carbon dioxide is placed in the buoy to strike the 
bell 800,000 blows, or enough to last for a period of four months without 
attendance. 28 

Operation of Railway Signals. Somewhat similar to the operation of 
bell buoys is the application of liquid carbon dioxide for operating railway 
signals in isolated spots. This use, however, has survived only on one 
American railroad system, and the forward strides in developing reliable 
storage battery-operated devices for such service has thrown some doubt 
on the necessity of resorting to gas pressure systems for such work. 

The Power Bottle. More recently the advantages of liquefied carbon 
dioxide as a source of power have been exploited in this country in the 
so-called "Prest-Air" power bottle, a small cylinder of carbon dioxide 
adapted to be carried in automobiles, and accompanied by a lifting jack 
in which a pressure piston is raised by admitting carbon dioxide to the 
jack cylinder. The device did not meet with wide acceptance and is today 
little used, although quite large numbers were placed in service in 1922 and 
1923. 29 In Europe power bottles are used considerably for producing 

n Z. ges. Kohlensaureind., 2, 507 (1895). 

"Hill, Walter, "Liquid Carbonic Acid," Newport (1875). 

"Carbonic Acid, 4, 48 (1906). 

Anon. f Engineering News-Record, 93, 783 (1924). 

Anon. f Scientific American, 130, 181 (1924). 



USES OF COMMERCIAL CARBON DIOXIDE 253 

far-reaching sound signals (Tyfon System of Krupp), for railway repair 
groups, for emergency or fire signals in small towns, motor boats, etc. 

Airplane Starters. Recent studies indicate the possibility of construct- 
ing carbon dioxide pressure starters for airplane motors more compact 
and of lighter weight than electric starters, and naturally more convenient 
than starters which must be operated from outside the pilot's position. 

Leak Testing. Small quantities of liquid carbon dioxide are regularly 
used in leakage testing, where carbon dioxide is especially favored for gas 
pressure tests of vessels that have been used in storing or manufacturing 
inflammable or explosive materials. While safe practice demands the 
cleaning of such vessels as thoroughly as possible before repair work is 
undertaken, the use of carbon dioxide eliminates all combustion explosion 
hazard in a fool-proof manner. An allied application is the clearing of 
obstruction from plumbing, where a cylinder of carbon dioxide affords 
a convenient portable means used by plumbers to generate sufficient pressure 
to dislodge obstructions not moved by gentler means. 

Cleaning Water Wells. A new and apparently unpublished use for 
carbon dioxide has been found in the cleaning of water wells. In this case, 
however, it is the solid form which is used to generate the pressure 
instead of the liquid. The well is closed off and solid carbon dioxide is 
dropped into it permitting the melting or vaporization of the substance 
to build up a pressure, which must be relieved through the water-bearing 
strata, thus dislodging obstructions in its path, and providing for increased 
well flow. The incidental effect in loosening and partially dissolving deposits 
of carbonate scale or scale having a carbonate binder may be of value, 
although precise information is not available. The depth of the well, 
character of the water-bearing strata, size of casing, temperature distribu- 
tion, possibility of escape from other points than through the points to 
be cleaned, and amount and size of the pieces of solid carbon dioxide 
used would seem to be some of the factors involved in practicing the method 
successfully, and the precise effect of these factors does not seem to have 
received research attention, although the method has been successfully 
used in a number of instances. The judgment of the practical man super- 
vising the cleaning appears to be sufficient in many cases to obtain a 
desired result. Further study would seem to be indicated and justified. 

Operating Paint Guns. An interesting mechanical use of carbon dioxide 
is its employment in place of compressed air for the operation of spray- 
painting equipment. 30 Compressed air has become so easily and cheaply 
available that carbon dioxide is now regularly used for this purpose only 
in the sign-painting trade, where the use is so intermittent and for such 
comparatively small painting jobs that many operators do not consider 
the first cost of compressor equipment justifiable. 

For Raising Beer. This application is of considerable importance to 
the carbon dioxide industry. A rather large proportion of the liquefied 

Sturcke, U. S. 1,294,190; 1,277,269; 1,303,987; 1,210,500; 1,283,823. 



254 CARBON DIOXIDE 

gas now sold, especially in this country, is used for this purpose. This 
application depends upon two factors. First, the pressure of the gas on 
the surface of the beer which forces it from a container usually located 
at a point lower than the dispensing tap. And second, the property of the 
gas to keep the beer fully carbonated at all times. Other mechanical devices 
have been developed for this purpose but the carbon dioxide cylinder still 
holds its place remarkably well. 

USES FOR GASEOUS CARBON DIOXIDE 

In this section the applications of carbon dioxide will be considered 
which depend to a considerable extent upon the chemical nature of the 
gaseous compound. It is perhaps obvious that such a classification is 
somewhat artificial because in many applications involving the use of 
gaseous carbon dioxide the liquid and solid also play some part. 

Carbonating Beverages. When carbon dioxide gas is dissolved in water 
the resulting solution contains besides the dissolved gas, a compound 
resulting from its combination with water and the ions produced from this 
compound. The result is a sparkling liquid with a characteristic taste for 
which the public has developed a liking. While this carbonated water is 
often consumed as such, it is more often mixed with syrups and flavoring 
materials to produce products sold under the names of "soda water," "pop," 
"tonic" and others. The bottling industry is a large and important part 
of our industrial structure and uses a very high percentage of the liquid 
carbon dioxide of commerce. 

The principal operation in the bottling industry in which carbon dioxide 
gas is used is the process of carbonating water. This is accomplished by 
means of automatic machinery which admits the gas under pressure to a 
carbonating chamber and brings about its solution by agitation. Many 
types of machines are used but the principle of operation is the same in 
all of them. 

Carbonated Milk. An interesting proposed use for carbon dioxide 
which has not been successfully commercialized is the proposal for the 
preparation of carbonated milk. 31 

Fire Extinguishing. The advantages of carbon dioxide gas for fire 
extinguishing have long been known but it was not until the growth of the 
extensive telephone system in the United States that attention became 
focussed upon the special fitness of carbon dioxide for certain types of 
fire extinction. 

As early as 1914, the Bell Telephone Company of Pennsylvania recog- 
nized the desirability of avoiding damage to wiring by extinguishing agents, 
and installed a number of 7-pound capacity hand extinguishers. These 
were steel cylinders of the conventional type (I.C.C. No. 3) equipped with 
the ordinary valve (4 inch bore), and provided with a rubber hose and 

81 Van Slyke, L. L. f and Bosworth, A. W., N. Y. Agri. Expt. Sta. Bull., 292 (1907). 



USES OF COMMERCIAL CARBON DIOXIDE 255 

nozzle taken from soda and acid extinguishers to facilitate directing the 
gas toward the fire. This crude device, despite its tendency to freeze and 
clog, and despite the fact that it entrains considerably more air than carbon 
dioxide, is quite effective on small telephone switchboard fires and remained 
in use in Pennsylvania for over a decade with fairly good results. 

At about this time there was also introduced in Europe a system for 
extinguishing fires in the holds of vessels known as the Gronwald system. 
Gronwald employed commercial cylinders of carbon dioxide, with a heating 
device which required warming up at the time of a fire before the cylinders 
could be exhausted, and used valves of such small bore the rate of dis- 
charge of the carbon dioxide was very limited. 32 

In the decade following the World War, however, renewed activity 
was shown in this field, and the use of liquefied carbon dioxide in extinguish- 
ing fires was greatly extended. The increased importance of carbon dioxide 
in this field can be attributed largely to the following general developments : 

1. Recognition of the necessity for employing either a siphon tube as 
proposed earlier by Camus or inverted cylinders as described by 
Luhmann in order to conduct liquid rather than gaseous carbon 
dioxide from the cylinder. 

2. The employment of larger valve openings promoting higher rates 
of discharge, with less likelihood of stoppages. 

3. The development of several types of dependable quick-opening 
valves suitable for the service. The requirement of a reliable quick- 
opening valve which would at the same time insure against leakage 
has been met by combining the functions of rupturable safety disc 
and valve. There are two general types: (a) Valves in which 
copper or gold-plated copper discs having a bursting pressure of 
2350 to 2950 Ibs. per sq. in. are used, combined with devices for 
punching a portion of the disc, shearing out a circular portion, 
punching out a star-shaped portion, or pulling through a piercing 
member from inside the disc by means of a pull wire soldered through 
the disc itself, (b) Valves in which a special light disc is employed, 
so light that it will rupture under normal cylinder pressure. The 
center portion of the disc is supported by a movable spud which 
prevents rupture of the disc until the extinguisher is to be dis- 
charged. Discharge is accomplished by merely removing the sup- 
port from the disc, which bursts, releasing the discharge. 

4. The development of nozzles suitably designed to prevent freezing 
or formation of carbon dioxide or water snow in a manner that 
would clog them. 

M The broader subject of marine fire extinguishing systems employing combustion gases is not 
treated here, since the purpose of such systems is primarily to obtain gases low in oxygen, the 
carbon dioxide per se playing a minor role. For an extended description of such systems see Trans. 
Inst. Marine Eng. t 24. 354-423 (1913). For a description of similar systems intended for use on 
land see Chetn. Met. Eng., 25, 513 and 729 (1921). On the application of flue gases- and occasionally 
pure COa as well to mine fires, see Mines and Minerals, 505 (1908); Trans. Inst. Min. Eng.. 17. 
181 (1900); Colliery Guardian, 505 (1916); Bull. Am. Inst. Mining Enars. (London), 55. 186 (1916); 
Coal Industry, 292 (1923); Quarterly Natl. Fire Protection Assoc., 17, 42-51 (1923). 



256 CARBON DIOXIDE 

5. The development of entrainment shields, usually of conical or cylin- 
drical form, to limit the amount of air or other gases entrained by 
the carbon dioxide at the point of discharge. 

6. The development throughout the fire extinguishing field of devices 
for automatically discharging extinguishers. These are arranged 
for immediate or delayed discharge, actuated either locally or 
remotely, and responsive to temperature, pressure, time, or rate of 
rise in temperature. 

A typical carbon dioxide hand extinguisher is shown in Figure 85. It 
has a carbon dioxide capacity of 7 or 15 pounds and is designed to dis- 




FICURE 85. ,. - 

'->!*, . 

Typical Hand Fire Extinguisher" 
Using Liquid Carbon Dioxide. 

Courtesy, American-LaFrance- 
Foamite Corporation. 



charge its contents of liquid in well under 1 minute, extending the dis- 
charge of the high pressure gas remaining in the cylinder after the liquid 
is gone for another 2 or 3 minutes. The discharge consists of a mixture 
of carbon dioxide gas and snow. The latter is thrown upon the fire, tending 
to chill it to some extent, and rendering the extinguisher considerably more 
effective than would be the case if carbon dioxide were used in gaseous 
form only. 

This type of extinguisher has become standard for the protection of 
telephone switchboards, and is widely used for first-aid fire protection in 
electrical hazards, inflammable liquids, small boats, garages, and the like. 
It has gained for itself an important place in fire protection engineering, 
suffering principally from two limitations its cost is somewhat higher 
than older forms of first-aid fire appliance, and its range is quite limited, 



USES OF COMMERCIAL CARBON DIOXIDE 



257 




Courtesy, American-La-France-Foamite Corporation. 
FIGURE 86. Carbon Dioxide Fire Extinguisher. 

requiring that it be employed not more than five feet from the fire. Off- 
setting these disadvantages, it has the great advantages that its operative- 
ness can be checked by simply weighing, that there is no deterioration of 
the charge, no necessity for periodic recharging, and no damage or hazard 
of any kind connected with the fire-extinguishing medium. 

Figure 86 shows the so-called "direct hose" apparatus in which the 
carbon dioxide is taken from cylinders of 50 or 100 pounds capacity. 

When fire protection is desired for ships, electrical machinery and 
spaces containing inflammable materials, a system is employed in which 
carbon dioxide is conducted, from a battery of steel cylinders, through 




Courtesy. Amcrican-LaFrance-Foamite Corporation. 

FIGURE 87. Battery of Carbon Dioxide Cylinders and Automatic Releasing 
Mechanism for Fire Extinguishing. A General Application of the Alfite System 
for an Industrial Hazard. 



258 



CARBON DIOXIDE 



permanent piping to the space to be protected. Automatic release of the 
carbon dioxide is usually provided for and the discharge nozzles carefully 
placed to direct the gas to the points best suited for obtaining the greatest 
efficiency. Figure 87 shows such a battery of carbon dioxide cylinders and 
the automatic, electrically operated, releasing mechanism. In Figure 88 is 
shown a typical installation for the protection of a space containing inflam- 
mable vapors. 




FIGURE 88. Typical Installation of Carbon Dioxide Fire Extinguishing Appa- 
ratus for Protecting Space Containing Inflammable Vapors. 

Figure 89 shows a test of a system in which the carbon dioxide is 
liberated below the surface of burning oil in an open tank. In this case 
the tank had an area of 400 square feet. 33 

For a more extended discussion of both theory and design, as well 
as records of successful performance of carbon dioxide extinguishers on 
fires, the reader is referred to the special literature on the subject. 34 

83 Quart. Natl. Fire Protection Assoc., 157 (1928). 

84 Sec "Regulations of the National Board of Fire Underwriters for Carbon Dioxide Fire 
Extinguishing Systems," obtainable from National Fire Protection Association, 60 Batterymarch 
St., Boston, Mass.; Jones, C. L., Quart. Natl. Fir* Protection Assoc. (1924); Moulton, R. S., Ibid., 
145-60 (1928); Ibid.. 271-288 (1930). 



USES OF COMMERCIAL CARBON DIOXIDE 



259 




Courtesy, American-LaFrance-Foamite Corporation. 

FIGURE 89. Testing Carbon Dioxide System for Extinguishing 
Oil Tank Fires. 



260 CARBON DIOXIDE 

Another application of liquid carbon dioxide to lire extinguishing differs 
somewhat from that just discussed as it depends more upon the power 
available from the liquid than upon the chemical properties of the gas 
itself. In this country and especially in Europe many thousands of small 
fire extinguishers are in use where small power bottles of liquid carbon 
dioxide eject extinguishing liquids or powders, as for instance, bicarbonates 
or carbon tetrachloride. 

Mention perhaps should also be made of the very important use of 
liquid carbon dioxide for the instantaneous extinguishing of the arc of 
high voltage switches. 

Preservation of Foods and Flowers. It is a pretty well established 
fact that atmospheres containing various amounts of carbon dioxide furnish 
environments in which bacteria do not thrive. Studies extending back for 
many years indicate that the carbon dioxide in carbonated beverages retards 
to varying degrees the development of bacteria which would otherwise find 
favorable conditions for growth. Recently much interest has been shown 
in the action of gaseous carbon dioxide to prevent spoilage of foods in 
general and especially to its preservative action on fruits, vegetables and 
meats. 35 

Preservation of Fruits. Brooks 30 found that it was possible by the use 
of solid carbon dioxide to secure a carbon dioxide content of the atmosphere 
in a railway car within 30 to 60 minutes which checks rotting and softening 
of warm fruit as much as would a 30 to 40 drop in temperature. It is 
necessary, however, that the gas escape within 18 to 24 hours to prevent 
injury to the flavor of the fruit, especially peaches, red raspberries and 
strawberries. Dewberries, blackberries, cherries and plums are more 
resistant to injury. Grapes, sweet corn, peas and beans offer the greatest 
promise of beneficial action of carbon dioxide in storage without harm to 
the product. 37 Harmful concentrations of carbon dioxide on certain types 
of vegetables under various conditions of gas storage have also been deter- 
mined by Thornton. 38 Trout 39 discovered that an atmosphere containing 
2 per cent of carbon dioxide retarded the ripening of pears and did not 
harm the fruit although the flavor was slightly affected. Kidd and West 40 
conducted storage experiments on Lane's Prince Albert apples which 
showed that the optimum conditions for preservation were 4 C. in an 
atmosphere containing 2.5 to 5 per cent carbon dioxide. Under these 
conditions the commercial storage life of the fruit was twice as long as that 
in air at the same temperature and nearly twice as long as that in air at 

83 Valley, G., Quart. Rev. Biol., 3, 209-24 (1928). This paper gives a general review of the 
literature up tu that date. 

* Brooks, Charles, Phytopathohay, 21, 103 (1931). 

37 See also, Brooks, C., Miller, E. V.. Bratley, C. O., Cooley, J. S., Mook, P. V., and Johnson, 
H. B., U. S. Dept. A<jr., Tech. Bull., 318 (1932). 

88 Thornton, N. C., Contrib. Boycc Thompson Inst., 3, 219-44 (1931). 

Trout, S. A., /. Pomology Hort. Set., 10, 27-34 (1932). 

"Kidd, F., and West, C., J. Pomology Hort. Set., 11, 149-70 (1933). 



USES OF COMMERCIAL CARBON DIOXIDE 261 

1.11 C. Miller and Brooks 41 found that peaches, corn and peas withstand 
treatments with 35 to 47 per cent carbon dioxide at 5 C. for 4 to 5 days 
without impairment of flavor. Treatment at higher temperatures produced 
a characteristic ripe flavor in 1 to 2 days. 

Preservation of Meat and Fish. Killcffer 42 tabulated the changes in pH 
on meat surfaces exposed to carbon dioxide, and gave data on experimental 
reduction of bacterial infection by exposure to the gas. He concluded that 
meat and fish can be kept fresh longer when refrigerated in a carbon dioxide 
atmosphere than in air. Lea 43 showed that the tainting of fat stored at 
C. was greatly retarded in an atmosphere of carbon dioxide. The inhibiting 
effect of carbon dioxide was greater when the fat was stored in the carbon 
dioxide atmosphere at once and when the humidity was reduced from 100 
per cent to 90 per cent. It has also been found 44 that the retarding effect 
of carbon dioxide on meat-attacking fungi is greater on growth than on 
germination of the mold spores. Thus in a 10 per cent carbon dioxide 
atmosphere at C. the growth rate was reduced to about 50 per cent of 
the value in air. 

Gas storage of fresh fish lias been investigated by Coyne 45 who found 
that various types of fish could be kept in carbon dioxide at C. for 
periods up to 28 days without serious deterioration, while controls stored 
in air were inedible after 12 to 14 days. Air containing 40 per cent carbon 
dioxide was as satisfactory as pure carbon dioxide. 

Preservation of Flowers. Thornton 46 has made a very thorough study 
of this field as well as the gas storage of fruits and vegetables. Table 70 
gives the results of a tabulation of considerable importance. Although this 
table expresses the effect in terms of carbon dioxide concentration causing 
injury, it is to be noted that many of the products investigated show bene- 
fits when treated with less than injurious quantities. Thus, rosebuds 
removed to warm air after a period of storage in 15 per cent carbon dioxide 
for 7 days at 3.3 C. or 10 C. lasted as well as untreated roses which had 
been in cold storage without carbon dioxide for 3 days a possible gain in 
shelf life of 4 days. 

Preservation of Eyys. The storage and shipment of eggs presents a 
special problem, since the carbon dioxide concentration in the air surround- 
ing an egg determines the equilibrium pH in the white of the egg. It has 
been found desirable to maintain a pH approximating as closely as possible 
that of the eggs when laid, and commercial carbon dioxide in both liquid 

41 Miller, E. V., and Brooks, C., J. Ayr. Research, 45, 449-59 (1923). 
Killeffer, D. H., Ind. Eng. Chcm.. 22, 140-3 (1930). 

Lea, C. II., Dept. Sci. Ind. Research Dept. Food Investigation Board 1932, 39-43 (1933), 
also J. Soc. Chem. Ind., 52, 9-12 T (1933). 

"Moran, T., Smith, E. C., ami Tomkins, R. G., /. Soc. Chem. Ind., 51, 114-16 T (1932); 
Tomkins, R. G., Ibid., 51, 361-4 T (1932). 

Coyne, F. P., /. Soc. Chem. Ind., 51, 119-21 T (1932); Ibid., 52, 19-24 T (1933). 

*" Thornton, N. C., Ind. Eng. Chem., 22, 1186-89 (1930); Am. J. Botanv.. 17, 614-26 (1930); 
Contrib. Boyce Thompson Institute, 3, 219-44 (1931); 5, 371-402 (1933); 5, 403-18 (1933); 5, 471-81 
(1933); 6, 395-402 (1934); 6, 403-5 (1934). 



262 



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8" 



PH 

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fc 



5 

fe 

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8 



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CARBON DIOXIDE 

CO O O CM 

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rt OCO CO CO CO CO O "5 i-i iO CM CM 

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IOCO CO OCO CMCOCOCO cOCMCMiOiOT-H e 0O 



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CO ^ CM 10 



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e 10 10 CM rt< rH rH CM CM OO 



CO CO 



r>- 1>- co t^- co co o i>- 1 




1 





^ 



USES OF COMMERCIAL CARBON DIOXIDE 



8 

fa 

o 

S 

fa 

S 

h 
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8 
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263 



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264 CARBON DIOXIDE 

and solid forms has been used for introducing the gas into the air of the 
storage rooms. 47 

Uses in the Canning Industry. Rector 48 has developed a method for 
canning food products in an atmosphere of inert gas. In this process the 
can is evacuated, and inert gas, usually drawn from steel cylinders, is 
injected. While the process is applicable with either carbon dioxide or 
nitrogen to any powdered or shredded food product subject to oxidation, 
such as coffee, nut-meats, powdered milk, cocoa products and the like, the 
best known commercial use is in the gas-packing of sweetened shredded 
cocoanut, where the lower pH maintained through the use of carbon dioxide 
in the can is of material assistance in controlling spoilage. 

Uses in the Chemical Industry. The most general use of carbon 
dioxide in the chemical industry is in the formation of carbonates. Large 
quantities are used in the Le Blanc, Clans-Chance, and ammonia-soda pro- 
cesses, more especially in the last named. In these reactions, however, as 
well as in the familiar Dutch process for manufacture of white lead, pure 
forms of commercial carbon dioxide need not be employed, and never are. 
It is hence customary to supply the necessary gas for carbonation in impure 
form, usually by burning lime. Since these arts are well developed and 
have a considerable literature of their own, they need not be considered 
further here. 49 The use of kiln gases in carbonating beet sugar solutions 
is also well covered in the literature pertaining to that industry. 

Manufacturing Carbonates. Small quantities of commercial carbon 
dioxide are used for the manufacture of certain carbonates such as chalk. 
A proposed use of commercial carbon dioxide of considerable interest to 
the manufacturers is in the production of wet or Carter process white lead, 
for which improved yield and quality of product are claimed. The price of 
the product has apparently never been sufficient to support the use of com- 
mercial grades of pure carbon dioxide for this purpose, yet the suggestion 
of manufacturing wet process white lead in commercial carbon dioxide 
plants during the slack winter season to improve annual load factors of 
plant operation has been seriously advanced, though not yet applied com- 
mercially. 

Kolbc Synthesis. Commercial liquid carbon dioxide was formerly 
employed to some extent in the manufacture of salicylic acid and aspirin 
from sodium phenolate. For economic reasons a large amount of the 
carbonic acid now required for this purpose in the United States is pro- 
duced by the calcination of carbonates. One large chemical company in 
New Jersey is now obtaining its carbon dioxide supply from liquefiers 
charged with the solid. .It is said that this practice is rather common in 
Great Britain. 

47 Sharp, P. F., Tec and Refrigeration, 78. 253 (1930). Shutt, F. T. t DcM. Aqr. Canada, Kept. 
Dominion Chemist for Year Ending March 31, 1930, 121 (1931). 

48 Rector, T. M., "Scientific Preservation of Foods," John Wiley and Sons, New York, (1925). 
19 See Hou, T. P., "The Manufacture of Soda with Special Reference to the Ammonia -Process," 

New York Chemical Catalog Co.. Inc., 1933. 



USES OF COMMERCIAL CARBON DIOXIDE 265 

Controlling Acidity. An interesting application of commercial carbon 
dioxide is in the control of pH, in which its usefulness lies in the ease of 
controlling its application to produce slight changes in pH. The principal 
point of application is to refrigerating brines. 50 The suggestion has also 
been advanced of using carbon dioxide to control the pH during the drying 
of sensitized film, where the control of concentration of carbon dioxide and 
ammonia in the air of the drying room affords a ready means of adjusting 
the pH to any point desired. 51 

As an Inert Gas. Perhaps the most obvious property leading to com- 
mercial application of carbon dioxide is to be found in the fact that it is the 
most readily available and least expensive commercial gas that may be 
regarded as "inert" or at least "non-oxidizing" in virtually all ordinary 
chemical operations. This is the basis of its use in deodorizing cod-liver 
oil and in supplying a non-oxidizing atmosphere in the containers in which 
it is handled. 52 Small quantities arc sold for use as a vehicle in the dis- 
tillation of phthalic anhydride and resort to the use of carbon dioxide for 
similar operations in the laboratory is not uncommon. Of interest also in 
this connection is the patent to Bacon/' 3 in which a current of carbon 
dioxide is relied upon to drive traces of sulfur dioxide out of fruit juices 
preserved by means of it, in order that there may be no sulfur dioxide in 
the finished product. There appears to be no published record of its com- 
mercial use for this purpose. It has also been proposed as an non-oxidizing 
gas in the handling of phosphorus, and preparation of phosphorus alloys. 54 
Lewis suggests its use in the manufacture of zinc oxide, using the gas as 
a non-oxidizing diluent to decrease particle size. 55 

As a Cheap Acid. The possible application of carbon dioxide as a 
mineral acid in neutralizing operations, and the fact that when shipped in 
solid form it is the only cheap, available, non-corrosive acid anhydride 
which may be shipped without special containers and handled easily and 
safely, does not seem to have engaged the attention of industrial researchers 
to any great extent. When it is considered that the material is now avail- 
able in a range of cost competitive with sulfuric acid in cost per pound of 
hydrogen ions, and that its shipping weight per pound of hydrogen ions 
is less than half that of the commoner mineral acids, it would seem likely 
that further applications to neutralizing operations will be found. Methods 
for rapid graphic calculation of such operations have been published, 50 and 
it is, of course, true that carbon dioxide may be regarded as a substitute for 
other acids in such operations as carbonation in beet sugar refining. 

60 Bush, R. J., Ice and Refrigeration. 81, 296-7 (1931). 
Morse, S., U. S. 1,493,000 (1924). 

"Nitardy, F. W., British 214,238 (1923); Heyerdahl, P. M., U. S. 1,368,148; Hamilton, U. S. 
1,745,851. 

"Bacon, R. F., U. S. 1,305,244 (1919). 

"Millring, E. R., U. S. 1,501,356 (1924). 

"Lewis, W. K., U. S. 1,442,265 (1923). 

"Dittmer, J. C., Chem. Met. Eng., 23, 1179 (1920). 



266 CARBON DIOXIDE 

Carbonic acid is a sufficiently strong acid to hydrolyze starch and sugar 
solutions, and has been proposed for commercial use, although no published 
record of such use appears to exist. The reaction is of great importance in 
explaining the rapid inversion of sucrose in carbonated beverages, however, 
and in that sense may be considered to be in daily use. 57 The role of carbon 
dioxide as a mineral acid is also found in the conversion of sodium chromate 
to bichromate under pressure. 58 

Carbonation of Water Supplies. This might well be considered as a 
chemical use, inasmuch as the purpose in every case is strictly chemical. 
The recarbonation of lime-softened domestic water supplies is either to 
reduce the pH of the treated water to a point less conducive to precipitation 
of carbonates, or to neutralize excess lime usually used in the process. It 
is almost always necessary in the lime-softening process, when it is desired 
to produce low alkalinity water, to use from 2 to 4 grains of lime per gallon 
of water treated, in excess of the molecular relation of lime to the hardness 
compounds. This excess lime, or high causticity, if left in municipal 
supplies, is objectionable because it increases the hardness and gives the 
water an alkaline taste. Excess lime is readily neutralized by carbon dioxide 
and its introduction into caustic settled softened water produces a second- 
ary insoluble precipitation of calcium carbonate which can readily be 
removed by settling or filtering. The combined use of excess lime and 
carbon dioxide makes it possible to reduce carbonate hardness to the lowest 
permissible degree. 

The solubility of mixed precipitate of calcium carbonate and magnesium 
hydroxide, the precipitate resulting from the lime reaction, is about 17 
p.p.m. and it is possible to reduce the carbonate hardness of water to this 
extent. Before the adoption of carbonation a reduction of carbonate hard- 
ness to 50 or 60 p.p.m. was considered to be about as good as could be 
attained and still have good tasting water. Practice has shown, however, 
that if the carbonate hardness is reduced to less than 30 or 35 p.p.m., corro- 
sion in pipe lines and hot water systems is apt to result ; therefore, 35 p.p.m. 
seems to be the lowest permissible limit to which carbonate hardness should 
be reduced. 

In practice, since the amount of carbon dioxide per volume of water 
is very small, it is customary to produce the carbon dioxide in the treating 
plant by combustion, using coke, natural gas, or in some small installations, 
kerosene; then scrubbing the flue gas to reduce the content of sulfur diox- 
ide, dust, or products of incomplete combustion that might impart a taste to 
the water and finally pumping the flue gases through diffusers or perforated 
pipes submerged in the water. While the method may be somewhat waste- 
ful from the point of view of carbon dioxide recovery, it is comparatively 
inexpensive and is in successful use in more than a score of American cities. 
It is considered amply justified by the greater reduction in hardness made 

"Dewey, M. A., and Krase, N. W., Ind. Eng. Chcm., 23, 1436-7 (1931). 
"Neumann, B. f and Exessner, C. f Z. angew. Chern., 43, 440 (1930). 



USES OF COMMERCIAL CARBON DIOXIDE 267 

possible, the savings effected through prolonged life of sand filters, increased 
flow through mains, and decreased trouble with incrustation throughout 
the water system, and it is reasonable to expect increased use of the 
method. 59 

Because of the steady requirement, the comparatively large daily 
demand, and the possibility of absorbing carbon dioxide directly from flue 
gases, commercial liquid or solid carbon dioxide has not yet been applied 
successfully to city water recarbonation. Their use, however, has been 
proposed, and it is believed that they may find some place in the field at a 
price in view of the certain purity and greater convenience of application 
for small installations. 

Removal of Scale with Carbon Dioxide. Closely allied to the recar- 
bonation use is the occasional use of commercial liquid or solid carbon 
dioxide in removing deposits of scale already formed in water systems. 
Such action is, of course, an incidental benefit from the reduction of pH 
when recarbonation is installed in a city where incrusted mains already 
exist, but the concentration of carbon dioxide applied to city water is natur- 
ally insufficient to effect the rapid emergency removal of scale from an 
industrial pipe system that has become too badly clogged with scale for 
further use. 

The removal of scale deposits by means of carbonated water appears to 
have been proposed by Greenhornc. 60 Cross and Irvin 61 further developed 
the idea, and made some practical trials. They described a method of 
determining the applicability of the scheme by treating samples of the 
deposit to be removed with carbonated water in pressure bottles and con- 
clude that the method is more satisfactory on deposits composed largely 
of silicates, having a binder of calcium carbonate than on deposits consisting 
largely of the carbonates themselves. 

A practical application of the method to the removal of scale from an 
obstructed line in the Duquesne works of the Carnegie Steel Company is 
described by Jones. 62 

Carbon Dioxide in the Rubber Industry. The use of carbon dioxide 
in the rubber industry today is limited to the filling of air bags used to 
support tires during vulcanization. This application has been developed 
by Minor, 63 who has proposed a method of using a combination of steam 
and carbon dioxide for inflating such bags. It is said that this method gives 
an increased life to the bag together with a close temperature control and 
increased vulcanization speed. 

"Eng. News-Record, 90, 671 (1923); Eng. Contr., 61, 1092 (1924); /. Am. Waterworks Assoc*, 
11, 393-408 (1924); Ibid., 11, 718 (1924); Chcm. Met. Eng., 35, 230 (1928). For more extensive dis- 
cussions of results in paiticular installations, see the Annual Reports of the Ohio Conference on 
Water Purification, obtainable from the office of the Secretary of State, Columbus, Ohio. 

Greenhorne, T. R., U. S. 1,135,684 (1915). 

"Cross, R. J., and Irvin, Roy, Power, 55, 422-23 (1922). 

"Jones, C. I-., Power, 60, 578-9 (1924). 

"Minor, H. R., India Rubber World, 49, 17 (1923). 



268 CARBON DIOXIDE 

Hardening of Cement Products. The relation of moisture and carbon 
dioxide from the air to the setting of Portland cement has been investi- 
gated, 04 and it is recognized that carbon dioxide plays a part by neutraliza- 
tion of the free alkali in the cement. The calcium carbonate thus formed 
strengthens the final product, and increases its density somewhat, naturally 
increasing the weight by the amount of the carbon dioxide absorbed. 

In contrast to this, when uncarbonated cement is submerged in water 
deficient in carbon dioxide, the free lime is removed by solution, leaving 
a lighter and more porous final product. 

Few Portland cement products are of sufficient value to justify the 
use of commercial carbon dioxide for their improvement, and hence the 
commercial use is limited to the carbon dioxide hardening of precast 
specialties on a restricted scale. For this purpose the formed pieces are 
placed in a curing room where a moisture content near saturation and a 
high carbon dioxide content is maintained. Increased use of the method, 
however, awaits only the reduction of the cost of carbon dioxide curing to 
a point commensurate with the value of the improvement obtained. 

Drying and Testing Cables. In Great Britain it has been found that 
carbon dioxide drawn from commercial steel cylinders is a more efficient 
drying agent for telephone cables than is calcium chloride dried air. The 
practice of drying out cables after laying does not seem to be favored in 
the United States ; hence neither expedient is used, and no carbon dioxide is 
sold in this country for this purpose. According to Gibbons, 05 field drying 
is accomplished about 25 per cent faster and at about half the expense with 
carbon dioxide as compared with dried air. 

Carbon dioxide finds some application in testing lead-sheathed cables 
for leakage. Obviously, if a gas is admitted under pressure at one end of a 
uniformly built cable and discharged at the other end, assuming no leakage, 
the pressure drop per unit of length from the admission point to the leak 
will be greater than that from the leak to the exhaust end, and greater than 
the average for the entire length. By the use of this principle and suitable 
pressure measurements along the cable, it is possible to locate leakage 
approximately without going over the entire cable. 

Chemical Control. A most interesting application to which carbon 
dioxide has been put in at least one case is for controlling the inflation of a 
metalclad air ship. 00 The high density of gaseous carbon dioxide and the 
ease with which it is chemically separated from other gases, especially 
helium, makes it especially adapted to this process. 

The inflation of the metalclad airship, the ZMC-2, was conducted in two 
stages. In the first stage the air in the hull was displaced by passing carbon 
dioxide into the bottom of the ship at a rate of about 10,000 cubic feet per 

Meyers, S. L. f Concrete, 18, 128-30 (1921). 

65 "Recent Developments in Underground Construction," Paper read before London Centre, 
Institution of Post Office Electrical Engineers, obtainable from Engincer-in-Chief Office G. P O. 
(West), E. C., London, England. 

M Carr, A. R., and T.ood, A. C., Itid. Eng. Chem., 22, 227 (1930). 



USES OF COMMERCIAL CARBON DIOXIDE 269 

hour. The displaced air was exhausted from the top of the hull. In the 
second stage helium was run into the hull at the top at a rate of about 10,000 
cubic feet per hour and the displaced carbon dioxide was discharged from 
the bottom. When the helium content of the escaping carbon dioxide 
reached about 48 per cent the gas was scrubbed with a caustic solution and 
the separated helium returned to the ship. 



Appendix 

List of Patents on Manufacture, Storage 
and Distribution of Solid Carbon Dioxide 

and 

Tables of Physical Data Calculated 
to English Engineering Units 

SATURATED LIQUID AND VAPOR 

Table No. 71 Vapor pressure of Liquid 

72 Specific Volume of Liquid 

73 Specific Volume of Vapor 

74 Density of Liquid 

75 Density of Vapor 

76 Enthalpy of Liquid 

77 Enthalpy of Vapor 

78 Heat of Vaporization of Liquid 

79 Entropy of Liquid 

80 Entropy of Vapor 

SATURATED SOLID AND VAPOR 

81 Vapor pressure of Solid 

82 Specific Volume of Solid 

83 Specific Volume of Vapor 

84 Density of Solid 

85 Density of Vapor 

86 Enthalpy of Solid 

87 Enthalpy of Vapor 

88 Heat of Sublimation of Solid 

89 Entropy of Solid 

90 Entropy of Vapor 



271 



272 



CARBON DIOXIDE 



LIST OF PATENTS 
Dealing with Solid Carbon Dioxide 

I. MANUFACTURE OF SOLID CARBON DIOXIDE 
(Methods and Apparatus) 



United States: 

No. 

579,866 
1,018,568 
1,546,681 
1,546,682 
1,600,308 
1,643,590 
1,659,431 
1,659,434 
1,659,435 
1,727,865 
1,735,094 
1,768,059 
1,795,772 
1,806,240 
1,810,989 
1,814,195 
1,818,816 
1,822,788 
1,843,397 

1,861,328 

1,863,263 

1,863,287 

1,863,377 

1,864,396 

1,869,346 

1,870,691 

1,875,164 

1,876,266 

1,877,180 

1,879,463 

1,884,313 

1,887,692 

1,893,850-1-2 

1,894,892 

1,895,886 

1,903,167-8-9-70-1 

1,912,443 

1,914,337 

1,919,698 

1,920,434 

1,925,041 

1,925,619 

1,927,173 

1,943,232 

1,949,179 

1,949,730 

1,950,180 



Elworthy, H. S. 

Julius, H. P. 

Slate, T. B. 

Slate, T. B. 

Blanchard, G. B. 

Slate, T. B. 

Josephson, W. S. 

Martin, J. W., Jr. 

Martin, J. W., Jr. 

Dehottay, IT. 

Slate, T. B. 

Hassensall, L. W. 

Goosmann, J. C. 

Donald, J. R. 

Smiley, O. 

Thomas, N. R. 

Rufener, H. and Eichmann, T. 

Stoffcls, J. 

Marcus, D. A. and Ogicr, 

W. W., Jr. 
Small, N. M. 
Belt, J. S. 
Small, N. M. 
Lockwood, E. J. 
Zumbro, F. R. 
Comer, W. T. 

Rust, R. R. and Jones, C. L. 
Schlumbohm, P. 
Weston, B. H. 
Jones, C. L. 
Petrequin, F. J. 
Small, J. D. 
Martin, J. W., Jr. 
Sullivan, E. G. 
Small, N. M. 
Lockwood, E. J. 
Cordrey, A. J. 
Goosmann, J. C. 
Belt, J. S. 
Hessling, W. 
Prescott, F. L. 
Auerbach, E. B. 
Zumbro, F. R. 

Jones, C. L. and Small, J. D. 
Zumbro, F. R. 
Pierce, R. C. 
Shoeld, M. 
Jones, C. L. and Small, J. D. 



March 30, 1897 
February 27, 1912 
July 21, 1925 
July 21, 1925 
September 21, 1926 
September 27, 1927 
February 14, 1928 
February 14, 1928 
February 14, 1928 
September 10, 1929 
November 12, 1929 
June 24, 1930 
March 10, 1931 
May 19, 1931 
June 23, 1931 
July 14, 1931 
August 11, 1931 
September 8, 1931 



February 2, 1932 
May 31, 1932 
~une 14, 1932 

une 14, 1932 
[une 14, 1932 

une 21, 1932 

uly 26, 1932 
August 9, 1932 
August 30, 1932 
September 6, 1932 
September 13, 1932 
September 27, 1932 
October 25, 1932 
November 15, 1932 

anuary 10, 1933 

anuary 17, 1933 

anuary 31, 1933 

VTarch 28, 1933 

une 6, 1933 

une 13, 1933 

uly 25, 1933 
August 1, 1933 
August 29, 1933 
September 5, 1933 
September 19, 1933 
January 9, 1934 
February 27, 1934 
March 6, 1934 
March 6, 1934 



APPENDIX 



273 



United States: 






No. 






1,965,922 


Fievet, H. 


July 10, 1934 


1,968,318 


Seligmann, A. 


July 31, 1934 


1,969,169 


Eichmann, T. 


August 7, 1934 


1,969,703 


Cribb, G. D. G. and Witby, 






W. H. 


August 7, 1934 


1,971,106 


Hasche, R. L. 


August 21, 1934 


1,972,240 


Rufcner, H. and Eichmann, T. 


September 4, 1934 


1,974,478 


Weber, G. 


September 25, 1934 


1,974,681 


Maiuri, G. 


September 25, 1934 


1,974,791 


Belt, J. S. and Cady, H. P. 


September 25, 1934 


1,976,777 


Goosmann, J. C. 


October 16, 1934 


1,978,508 


Reich, G. T. 


October 30, 1934 


1,979,556 


Jones, C. L. and Fitzpatrick, 


November 6, 1934 




W. H. 




1,981,675 


Stapp, P. 


November 20, 1934 


1,984,249-50 


Chamberlain, J. R. 


December 11, 1934 


Austria: 






114,103 


Lejune, F. 


March 15, 1929 


119,947 


Hamburger, Hermann and 






Hamburger, Hugo 


June 15, 1930 


Belgium: (Includes distribution and storage). 


353,014 


Hcssling, W. 


July 23, 1928 


355,51 1 


Dryice Corp. of America 


November 5, 1928 


356,242 


Lindc's Eismachinen A.-G. 


1928 


357,269 


Escher, Wyss and Cie 


1928 


357,643 


Mid. Europ. Octr. Maatsch. 


January 25, 1929 


359,300 


L'Acidc Carb. Pur. 


March 26, 1929 


359,699 


Solid Carbonic Co. 


April 9, 1929 


363,100 


L'Acidc Carb. Pur. 


August 19, 1929 


364,840 


Stapp-Munchcn 


October 2(5, 1929 


365,199 


Stapp-Munchen 


November 9, 1929 


Brazil: 






18,617 


Mid. Europ. Octr. Maatsch 


July 8, 1930 


Great Britain: 






2,450 


Elworthy, E. G. 


July 26, 1906 


7,436 


El worthy, II. S. 


February 15, 1895 


10,378 


Hall, L. B. 


March 23, 1911 


13,684 


Tichbornc, C. R. C. 


August 3, 1892 


27,576 


Read, H. V. R. 


1909 


237,681 


Slate, T. B. 


May 23, 1924 


294,584 


Hessling, W. 


July 26, 1927 


294,614 


Hcssling, W. 


July 27, 1927 


298,792 


Dryice Corp. of America 


November 15, 1927 


298,910 


Hessling, W. 


October 15, 1927 


301,741 


Gcs. fur Lindc's Eismachinen 


December 15, 1927 




A.-G. 




302,070 


Dryice Corp. of America 


January 17, 1928 


302,359 


Hcssling, W. 


December 15, 1927 


304,958 


DuBois, E. 


April 3, 1928 


312,231 


Cole, H. W. and McLaren, 


May 28, 1928 




M. W. 




314,371 


Mid. Europ. Octr. Maatsch'. 


June 26, 1928 


322,807 


Mortimer, J. E. 


September 14, 1928 


327,414 


Solid Carbonic Co., Ltd. 


December 31, 1928 


329,772 


Solid Carbonic Co., Ltd. 


February 15, 1929 


331,077 


Dryice Equipment Corp. 


June 13, 1929 



274 



CARBON DIOXIDE 



Great Britain: 

No. 

333/212 
341,361 
343,012 
345,229 
347,050 

348,581 
350,532 
353,014 
355,602 
355,923 
358,820 



360,166 
363,827 
363,870 
364,322 



367,492 
368,364 
369,629 
378,490 
389,475 
394,039 
404,833 

408,458 

408,459 
415,659 

Canada: 
285,166 
285,526 

Cuba: 

8,989 

Czecho-Slovakia: 
4,857 
4,890 

France: 

642,057 
645,020 
649,395 
649,396 
649,483 
652,094 
657,969 
667,827 
668,298 
672,767 
672,825 
673,129 
677,429 
678,330 
705,190 



Peggs, K. C. 

A.-G. fur Kohlensaure-Industrie 

Stapp, P. 

Rudd, H. B. 

Machinenfabrik Esslingen and 

Stoffels, J. 
Ficvet, II. 

Jones, C. L. and Small, J. D. 
Frankl, M. 
Cribb, G. D. G. 
Frankl, M. 
Brotherhood, P., Dunkcrley, 

H. M. and Carbon Dioxide Co. 

Ltd. 

Priestley, W. C. ' 
Small, J. D. 
Orison, J. 
Brotherhood, P., Dunkcrley, II. 

M. and The Carbon Dioxide 

Co. Ltd. 
Weber, G. 

Rust, R. R. and Jones, C. L. 
Comer, W. T. 
Smith, W. L. 

Foster, F. H. and Priestley, W. C. 
Brier, H. and Brier, J. H. 
Ges. fur Linde's Eismachinen 

A.-G. 
Cribb, G. D. G. and Whitby, 

W. H. 

Mid. Europ. Octr. Maatsch. 
Maiuri Refrig. Patents Ltd. and 

Maiuri, G. 

Martin, J. W., Jr. 
Josephson, W. S. 



May 6, 1929 
April 27, 1929 
November 7, 1929 
November 17, 1928 

September 20, 1929 
February 13, 1930 
March 28, 1929 
April 16, 1929 
November 18, 1930 
August 19, 1929 



December 24, 1930 
October 18, 1930 
December 19, 1929 
January 28, 1931 



December 23, 1930 
February 25, 1932 
February 29, 1932 
March 23, 1932 
August 8, 1932 
March 13, 1933 
June 22, 1933 

January 25, 1934 

April 12, 1934 
April 12, 1934 

August 30, 1934 

November 27, 1928 
December 11, 1928 



Cole, H. W. and McLaren, M. W. October 23, 1929 



Hessling, W. 
Lejeune, F. 



Soc. Anon, des Ateliers 

Dryice Corp. of America 

Vieillard, J. H. J. 

Vieillard, J. II. J. 

Dryice Corp. of America 

L'acide carb. pur (Soc. Anon.) 

Hessling, W. 

Mid. Europ. Octr. Maatsch. 

Soc. Anon, des Ateliers 

L'acide carb. pur. 

The Solid Carbonic Co., Ltd. 

Baumann, C. 

La carbonique francaise 

Lejeune, F. 

I. G. Farbenind. A.-G. 



July 25, 1928 
July 10, 1929 



October 7, 1927 
November 29, 1927 
October 27, 1927 
October 28, 1927 
February 7, 1928 
April 3, 1928 
July 23, 1928 
January 1, 1929 
November 2, 1928 
April 6, 1929 
April 8, 1929 
April 16, 1929 
June 26, 1929 
~uly 12, 1929 
'ovember 6, 1930 



4 
Ju 

N 



APPENDIX 



275 



France: 
No. 

739,816 
743,537 
763,883 
765,163 

Germany: 
484,570 
485,655 
493,478 
493,792 
508,168 
511,018 
513,514 
513,528 

514,717 
535,647 
537,764 
538,081 
540,069 
547,266 
550,474 
564,757 
578.825 
579,624 
581,302 
581,727 

599,3(57 

Hungary: 
98,321 
98,928 

Italy: 

11,262 

Japan: 

89,547 

90,628 

Switzerland: 
129,688 
129,690 
131,443 
136,481 
136,742 
137,132 
138,986 
141,393 
143,815 
154,917 



Goosmann, J. C. 
Hessling, W. 

Carbonic Development Corp. 
Office national ind. cie 1'azote 



Hessling, W. 

Hessling, W. 

Hagstotz, W. 

The Solid Carbonic Co., Ltd. 

Machincnfabrik Esslingen 

Machinenfabrik Esslingen 

Fehrmann, K. 

Ges. fur Linde's Eismachinen 

A.-G. 

Mid. Europ. Octr. Maatsch. 
Rudd, H. B. 

Soc. la carbonique francaise 
I. G. Farbenind. A.-G. 
Grison, J. and Morton, C. R. 
Dryice Corp. of America 
Stapp, P. 
Frcundlich, F. A. 
Stapp, P. 

I. G. Farbenind. A.-G. 
Dryice Corp. of America 
Ges, fur Linde's Eismachinen 

A.-G. 
Gcs. fur Linde's Eismachinen 

A.-G. 

L'acide carb. pur. 

Mid. Europ. Octr. Maatsch. 



Pegna, E. G. 



Okoti, M., Oyama, Y. and Inst. 
of Phys. and Chem. Research 
Okoti, M. and Oyama, Y. 



Hessling, W. 
Hessling, W. 
Escher Wyss and Cic. 
Escher Wyss and Cie. 
Escher Wyss and Cie. 
Escher Wyss and Cie. 
Baumann, C. 
Escher Wyss and Cie. 
Stapp, P. 
Weber, G. 



July 8, 1932 
April 1, 1933 
May 8, 1934 
June 4, 1934 



July 22, 1929 
August 1, 1928 
March 22, 1929 
March 12, 1929 
April 8, 1928 
September 21, 1929 
November 4, 1928 

April 17, 1929 
September 4, 1928 
November 16, 1929 
June 19, 1930 
December 8, 1929 
February 13, 1931 
November 18, 1927 
September 13, 1928 
January 18, 1931 
June 17, 1933 
July 1, 1933 
July 27, 1933 

August 1, 1933 
July 3, 1934 

September 4, 1928 
March 16, 1929 



February 19, 1929 



December 13, 1930 
March 13, 1931 



October 15, 1927 
July 27, 1927 
January 18, 1928 
October 11, 1928 
October 29, 1928 
December 24, 1928 
April 2, 1929 
October 19, 1929 
November 7, 1929 
February 2, 1931 



276 



CARBON DIOXIDE 



II. APPLICATIONS OF SOLID CARBON DIOXIDK 
(Methods and Apparatus) 



United States: 

No. 

1,592,993 
1,595,426 
1,634,089 
1,712,701 
1,735,082 
1,735,832 
1,736,706 
1,805,493 
1,825,073 
1,832,473 
1,852,388 
1,855,313 
1,870,684 
1,873,101 
1,873,364 
1,874,091 
1,877,181 
1,877,187 
1,878,042 
1, 893,228 
1,893,277 
1,893,483 
1,901,000 
1,924,059 
1,933,256-7-8 
1,941,744 
1,951,074 

1,951,758 
1,965,205 
1,975,177 
1,977,919 

Austria: 
136,291 

Great Britain: 
301,764 

France: 
661,487 
661,779 

Germany: 
557,162 
558,072 
583,263 



Slate, T. B. 

Slate, T. B. 

Slate, T. B. 

Hasscnsall, L. W. 

Martin, J. W., Jr. 

Martin, J. W., Jr. 

Jones, A. 

Martin, J. W., Jr. 

Killcffcr, D. H. 

Payson, A. E. and Wctmorc.M. P. 

Wilcox, W. D. 

Rudd, II. B. 

Killeffer, D. II. 

Banning, T. A., Jr. 

Taylor, II. M. 

Fahrney, E. H. 

Killeffer, D. H. 

Martin, J. W., Jr. 

Wagner, J. S. et al 

Oopeman, L. O. 

Eggleston, L. \V. 

Belt, J. S. 

Robe, W. B. 

Haskins, W. 

Goosmann, J. C. 

Hey wood, F. 

Warren, G. A. and Simpson, 

W. B., Jr. 
Jones, C. L. 
Smith, W. L. 
Shcrrick, S. T. 
Reiss, L. P. 



Stark, L. 
Dehottay, H. 



Dry ice Equipment Corp. 
Dryice Equipment Corp. 



Wolfinger, A. and Surany, V. 
Wolfinger, A. and Surdny, V. 
Alvarez, E. and Dauphin, A. L. ? 



July 20, 1926 
August 10, 1926 
June 28, 1927 
May 14, 1929 
November 12, 1930 
November 12, 1930 
November 19, 1930 
May 19, 1931 
September 29, 1931 
November 17, 1931 
April 5, 1932 
April 26, 1932 
August 9, 1932 
August 23, 1932 
August 23, 1932 
August 30, 1932 
September 13, 1932 
September 13, 1932 
September 20, 1932 
January 3, 1933 
January 3, 1933 
January 10, 1933 
March 14, 1933 
August 22, 1933 
October 31, 1933 
January 2, 1934 

March 13, 1934 
March 20, 1934 
Tuly 3, 1934 
October 2, 1934 
October 23, 1934 



January 25, 1934 
August 30, 1927 



October 4, 1928 
October 3, 1928 



April 15, 1930 
October 30, 1930 
August 31, 1933 



APPENDIX 



277 



III. MELTING AND VAPORIZING OF SOLID CARBON DIOXIDE 



United States: 






No. 






1,742,957 


Stoffels, J. 


January 7, 1930 


1,760,953 


Martin, J. W., Jr. 


June 3, 1930 


1,866,192 


Comer, W. T. 


July 5, 1932 


1,928,396 


Seek, F. C. 


September 26, 1933 


1,938,034 


Lundy, T. F. 


December 5, 1933 


1,943,820 


Goosmann, J. C. 


January 16, 1934 


1,951,758 


Jones, C. L. 


March 20, 1934 


1,957,640 
1,972,771 


Orison, J. 
Haid, W. S. and Terrell, P. A. II. 


May 8, 1934 
September 4, 1934 


Great Britain: 






331,750 


Machinenfabrik Esslingen and 






Stoffels, J. 


September 3, 1929 


366,239 


Comer, \V. T. 


January 18, 1930 


376,863 


Lukacs, E. 


May 22, 1930 


France: 






765,441 


Mosonyi, J. 


June 9, 1934 


Germany: 






474,133 


Machinenfabrik Essl ingen 


April 8, 1928 


493,941 


Hagstotz, W. 


March 22, 1929 


592,118 


Stapp, P. 


February 1, 1934 


Switzerland: 






147,557 


Hessling, \V. 


October 15, 1930 



IV. STORAGE AND TRANSPORTATION- 
(Methods and Apparatus) 



United States: 
1,786,161 
1,825,647 
1,885,769 
1,945,689 
1,980,727 

Great Britain: 

300,985 
388,212 
412,814 

Germany: 

561,815 
594,562 

Switzerland: 
128,819 
147,556 



{ones, C. L. and Small, J. D. 
lartin, J. W., Jr. 
Schlumbohm, P. 
Hults, E. A. 
Hults, E. A. 



Martin, J. W., Jr. 
Schlumbohm, P. 
Dehottay, TI. 



Schlumbohm, P. 
Geppcrt, H. 



Hessling, W. 
Hessling, W. 



December 23, 1930 
September 29, 1931 
November 1, 1933 
February 6, 1934 
November 13, 1934 



November 22, 1927 
February 23, 1933 
July 5, 1934 



April 20, 1930 
March 19, 1934 



March 15, 1928 
September 15, 1930 



278 



CARBON DIOXIDE 



Tables of Physical Data Calculated to English 
Engineering Units 

SATURATED LIQUID AND VAPOR 



TABLE 71. Vapor Pressure of Carbon Dioxide in Ibs. pet sq. in. 

(g.= 980.665) 
(By Meyers and Van Duscn) 



p. 





1 2 


3 


4 


5 


6 


7 


8 


9 


-69.86 


75.14 


Triple point 
















-60 


94.75 


92.60 90.49 


88.42 


8639 


84.38 


82.42 


80.48 


78.59 


76.72 


-60 


118.27 


115.74 113.25 


110.81 


108.40 


106.02 


103.69 


101.40 


99.15 


96.93 


-40 


145.87 


142.91 140.00 


137.14 


134.31 


131.53 


128.80 


126.11 


123.45 


120.84 


-30 


177.97 


174.54 171.17 


167.84 


164.56 


161.33 


158.15 


155.01 


151.92 


148.87 


-20 


215.02 


211.08 207.19 


203.36 


199.57 


195.85 


192.17 


188.55 


184.97 


181.45 


-10 


257.46 


252.96 248.52 


244.13 


239.81 


235.53 


231.32 


227.16 


223.06 


219.01 


- 


305.76 


300.65 295.61 


290.62 


285.70 


280.85 


276.05 


271.31 


266.63 


262.02 


+ o 


305.8 


310.9 316.2 


321.5 


326.8 


332.2 


337.7 


343.3 


348.9 


364.6 


10 


360.4 


366.2 372.1 


378.1 


384.1 


390.2 


396.4 


402.6 


409.0 


415.4 


20 


421.8 


428.4 435.0 


441.7 


448.4 


455.3 


462.2 


469.2 


476.3 


483.4 


30 


490.6 


497.9 505.3 


512.8 


520.3 


5280 


535.7 


543.5 


551.3 


559.3 


40 


567.3 


676.5 583.7 


592.0 


600.4 


608.9 


617.5 


626.1 


634.9 


643.7 


50 


652.7 


661.7 670.8 


680.0 


689.4 


698.8 


708.3 


717.9 


727.6 


737.5 


60 


747.4 


757.4 767.5 


777.7 


788.1 


798.6 


809.1 


819.8 


830.6 


841.5 


70 


852.5 


863.6 874.9 


8862 


897.7 


909.3 


921.1 


933.0 


945.0 


957.1 


80 


969.3 


981.7 994.2 


1006.9 


1019.7 


1032.7 


10457 


1058.9 






87.08 


1072.1 


Critical point 

















TABLE 72. Specific Volume of Carbon Dioxide Liquid in cu.fl. per Ib. 
(Data of Plank and Kuprianoff ) 



p. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


-69.9 


.01360 


Triple point 


-60 


.01384 


.01381 


.01378 


.01376 


.01373 


.01371 


.01369 


.01366 


.01363 


.01361 


-50 


.01409 


.01406 


.01403 


.01400 


.01398 


.01396 


.01393 


.01391 


.01389 


.01386 


-40 


.01437 


.01433 


.01430 


.01427 


.01425 


.01422 


.01419 


.01416 


.01414 


.01411 


-30 


.01465 


.01462 


.01458 


.01456 


.01454 


.01450 


.01447 


.01445 


.01442 


.01439 


-20 


.01498 


.01494 


.01491 


.01488 


.01485 


.01481 


.01478 


.01475 


.01472 


.01468 


-10 


.01533 


.01529 


.01525 


.01522 


.01518 


.01514 


.01511 


.01508 


.01504 


.01601 


- 


.01571 


.01567 


.01563 


.01559 


.01555 


.01551 


.01547 


.01544 


.01540 


.01536 


+ o 


.01571 


.01575 


.01579 


.01583 


.01587 


.01592 


.01597 


.01601 


.01605 


.01609 


+ 10 


.01614 


.01618 


.01623 


.01628 


.01632 


.01636 


.01642 


.01646 


.01650 


.01656 


+20 


.01662 


.01667 


.01672 


.01678 


.01684 


.01689 


.01695 


.01701 


.01707 


.01713 


+30 


.01719 


.01725 


.01731 


.01737 


.01743 


.01750 


.01757 


.01764 


.01771 


.01778 


+40 


.01786 


.01794 


.01801 


.01809 


.01817 


.01825 


.01834 


.01842 


.01852 


.01860 


+60 


.01867 


.01877 


.01887 


.01896 


.01906 


.01916 


.01926 


.01936 


.01948 


.01959 


+60 


.01970 


.01982 


.01997 


.02009 


.02012 


.02035 


.02049 


.02064 


.02079 


.02093 


+70 


.02109 


.02127 


.02146 


.02166 


.02188 


.02212 


.02240 


.02270 


.02300 


.02336 


+80 


.02370 


.02414 


.02458 


.02504 


.02556 


.02619 


.02686 


.02794 






+87.8 


.03453 


Critical point 



APPENDIX 



279 



TABLE 73. Specific Volume of Saturated Carbon Dioxide Vapor in cu.ft./lb. 
(Data of Plank and Kuprianoff) 



F. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


-69.9 
-60 


1.1570 
.9520 


Triple 
.9440 


point 
.9650 


.9865 


1.0100 


1.0360 


1.0590 


1.0831 


1.1095 


1.1340 


-50 


.7500 


.7670 


.7840 


.8000 


.8180 


.8350 


.8520 


.8690 


.8875 


.9055 


-40 


.6113 


.6245 


.6380 


.6520 


.6660 


.6790 


.6930 


.7060 


.7200 


.7338 


30 


.5025 


.5127 


.5210 


.5315 


.5420 


.5530 


.5650 


.5760 


.5880 


.6000 


-20 


.4165 


.4240 


.4325 


.4415 


.4500 


.4585 


.4670 


.4760 


.4845 


.4935 


-10 


.3465 


.3530 


.3590 


.3666 


.3725 


.3795 


.3865 


.3940 


.4015 


.4090 


- 


.2905 


.2958 


.3012 


.3065 


.3118 


.3173 


.3228 


.3285 


.3345 


.3405 


+ 


.2905 


.2852 


.2800 


.2753 


.2708 


.2660 


.2610 


.2565 


.2520 


.2475 


+ 10 


.2435 


.2395 


.2350 


.2310 


.2274 


.2232 


.2195 


.2158 


.2120 


.2082 


+20 


.2048 


.2015 


.1978 


.1945 


.1910 


.1878 


.1845 


.1813 


.1782 


.1750 


+30 


.1720 


.1690 


.1663 


.1635 


.1605 


.1578 


.1550 


.1522 


.1495 


.1468 


+40 


.1442 


.1417 


.1390 


.1365 


.1342 


.1320 


.1298 


.1275 


.1250 


.1228 


+50 


.1204 


.1185 


.1163 


.1142 


.1122 


.1111 


.1080 


.1060 


.1038 


.1013 


+60 


.0995 


.0978 


.0960 


.0940 


.0920 


.0900 


.0880 


.0860 


.0842 


.0822 


+70 


.0800 


.0780 


.0760 


.0740 


.0720 


.0700 


.0680 


.0667 


.0640 


.0620 


+80 


.0600 


.0580 


.0560 


.0540 


.0520 


.0500 


.0479 


.0430 






+87.8 


.0345 


Critical point 



TABLE 71. Density of Liquid Carbon Dioxide in Ibs./cu. ft. 
(Data of Plank and Kuprianoff) 



-69.9 


73.53 


Triple point 


-60 


72.27 


72.40 


72.53 


72.65 


72.78 


72.91 


73.04 


73.17 


73.30 


73.42 


50 


70.96 


71.10 


71.23 


71.36 


71.49 


71.62 


71.75 


71.88 


72.01 


72.14 


-40 


69.61 


69.75 


69.88 


70.02 


70.15 


70.28 


70.42 


70.55 


70.68 


70.82 


-30 


68.21 


68.35 


68.49 


68.63 


68.77 


68.91 


69.05 


69.19 


69.33 


69.47 


-20 


66.76 


66.91 


67.06 


67.20 


67.35 


67.49 


67.64 


67.79 


67.93 


68.07 


-10 


65.25 


65.41 


65.56 


65.71 


65.86 


66.01 


6626 


66.31 


66.46 


66.61 


- 


63.65 


63.82 


63.98 


64.14 


64.30 


64.46 


64.62 


64.78 


64.93 


65.09 


+ o 


63.65 


63.48 


63.31 


63.15 


62.98 


62.81 


62.64 


62.47 


62.30 


62.13 


+ 10 


61.96 


61.78 


61.60 


61.42 


61.23 


60.04 


6085 


60.67 


60.50 


60.32 


+20 


60.13 


59.93 


59.74 


59.54 


59.35 


59.17 


58.98 


58.78 


58.58 


68.37 


+30 


58.16 


57.95 


67.73 


57.52 


57.31 


67.10 


56.88 


56.66 


56.44 


56.21 


+40 


55.98 


55.75 


55.52 


55.29 


55.06 


54.83 


54.60 


54.35 


54.09 


53.83 


+50 


53.56 


53.30 


53.03 


52.76 


52.50 


52.23 


51.95 


51.66 


51.36 


51.06 


+60 


50.80 


50.50 


50.20 


49.90 


49.60 


49.26 


48.90 


48.53 


48.11 


47.75 


+70 


47.35 


46.95 


46.50 


46.05 


45.60 


45.10 


44.60 


44.06 


43.51 


42.96 


+80 


42.36 


41.75 


41.05 


40.30 


39.50 


38.50 


37.23 


35.20 






+87.8 


28.96 


Critical point 



TABLE 75.Density of Saturated Carbon Dioxide Vapor in Ibs./cu. ft. 
(Data of Plank and Kuprianoff) 



-69.9 


.861 


Triple point 


-60 


1.085 


1.062 


1.039 


1.016 


.993 


.970 


.947 


.924 


.904 


.885 


-50 


1.335 


1.310 


1.285 


1.260 


1.232 


1.205 


1.180 


1.155 


1.130 


1.107 


-40 


1.636 


1.605 


1.574 


1.542 


1.510 


1.480 


1.450 


1.420 


1.390 


1.361 


-30 


1.985 


1.948 


1.910 


1.875 


1.840 


1.805 


1.770 


1.735 


1.700 


1.668 


-20 


2.395 


2.350 


2.310 


2.270 


2.230 


2.182 


2.142 


2.101 


2.061 


2.023 


-10 


2.880 


2.830 


2.780 


2.734 


2.685 


2.637 


2.687 


2.535 


2.485 


2.440 


- 


3.450 


3.390 


3.330 


3.270 


3.209 


3.144 


3.082 


3.037 


2.985 


2.930 


h 


3.450 


3.510 


3.570 


3.630 


3.694 


3.758 


3.820 


3.890 


3.965 


4.040 


-10 


4.115 


4.190 


4.260 


4.330 


4.401 


4.480 


4.560 


4.640 


4.720 


4.800 


-20 


4.890 


4.978 


5.060 


6.144 


5.230 


5.320 


5.415 


5.510 


6.600 


5.700 


-30 


5.800 


5.905 


6.012 


6.110 


6.220 


6.335 


6.450 


6.570 


6.690 


6.815 


-40 


6.935 


7.064 


7.180 


7.310 


7.440 


7.570 


7.710 


7.850 


8.000 


8.150 


-50 


8.303 


8.458 


8.618 


8.778 


8.940 


9.100 


9.280 


9.470 


9.660 


9.864 


-60 


10.07 


10.28 


10.48 


10.70 


10.92 


11.14 


11.36 


11.60 


11.87 


12.14 


-70 


12.44 


12.76 


13.08 


13.42 


13.86 


14.22 


14.58 


14.98 


15.40 


15.92 


-80 


16.44 


16.98 


17.58 


18.20 


18.92 


19.78 


20.88 


23.40 






-87.8 


28.96 


Critical point 



280 CARBON DIOXIDE 

TABLE 76. Enthalpy of Liquid Carbon Dioxide in B. t. u. lib. 
(Data of Plank and Kuprianoff) 



-69.9 


129.5 


Triple 


point 
















-60 


134.1 


133.6 


133.1 


132.7 


132.3 


131.8 


131.3 


130.9 


130.4 


129.9 


-50 


138.6 


138.2 


137.7 


137.2 


136.8 


136.4 


135.9 


135.4 


135.0 


134.6 


-40 


143.2 


142.8 


142.3 


141.8 


141.4 


140.9 


140.5 


140.0 


139.6 


139.1 


-30 


147.9 


147.4 


147.0 


1465 


146.0 


1456 


145.1 


144.6 


144.2 


143.7 


-20 


152.4 


152.0 


151.5 


151.1 


1506 


150.2 


149.7 


149.3 


148.8 


148.3 


-10 


157.1 


156.6 


156 1 


1558 


155.3 


154.9 


154.4 


154.0 


153.5 


153.0 


- 


162.0 


161.6 


161.1 


160.6 


160.1 


159.6 


159.1 


158.7 


158.2 


157.7 


+ o 


162.0 


1625 


163.0 


163.5 


164.0 


164.5 


165.0 


165 5 


166.1 


166.6 


+ 10 


167.2 


167.7 


168.2 


168.8 


169.4 


170.0 


170.5 


171.1 


171.7 


172.2 


+20 


172.8 


173.4 


174.0 


174.5 


175.0 


175.7 


176.3 


176.9 


177.5 


178.2 


+30 


178.8 


179.4 


180.0 


180.6 


181.2 


181.9 


182.5 


183.1 


183.7 


184.4 


+40 


185.0 


185.6 


186.3 


187.0 


187.6 


188.2 


188.9 


189.6 


190.3 


191.0 


+50 


191.7 


192.4 


193.1 


193.8 


194.5 


195.2 


196.0 


196.7 


197.4 


198.2 


+60 


198.9 


199.7 


200.4 


201 2 


202.0 


2028 


203.6 


204.4 


205.2 


206.1 


+70 


206.9 


207.8 


208.8 


209.7 


210.7 


211.8 


212.8 


213.9 


215.0 


218.1 


+80 


217.2 


218.5 


2198 


221.2 


222.8 


224.6 


226.6 


230.8 






+87.8 


240.3 


Critical point 



TABLE IT. Enthalpy of Carbon Dioxide Vapor in B.t.ujlb. 
(Data of Plank and Kuprianoff) 



-69.9 


279.16 


Triple point 


-60 


279.90 


279.83 


279.75 


279.68 


279.62 


279.55 


279.48 


279.40 


279.37 


279.20 


-50 


280.52 


280.46 


280.40 


280.32 


280.28 


280.23 


280.18 


280.10 


280.03 


279.97 


-40 


281.11 


281 05 


280.98 


280.83 


280.88 


280.82 


280.78 


280.72 


280.65 


280.60 


-30 


281.54 


28150 


281.47 


281.43 


281.38 


281.34 


281.28 


281.25 


281.20 


281.16 


-20 


281.87 


281.84 


281.81 


281.78 


281.75 


281.71 


281.67 


281.64 


281.61 


281.57 


-10 


282.05 


282.04 


282.03 


28201 


281.99 


281.97 


281.95 


281.93 


281.91 


281.89 


- 


282.10 


282.10 


282.10 


282.10 


282.10 


282.09 


282.09 


282.08 


282.07 


282.06 


+ o 


282.10 


282.09 


282.08 


282.08 


282.07 


282.06 


282.05 


282.04 


282.02 


282.00 


+ 10 


281.98 


281.96 


281.94 


281.91 


281.88 


281.85 


281.82 


281.79 


281.76 


281.72 


+20 


281.68 


281.64 


281.59 


281.54 


281.47 


281.40 


281.33 


281.27 


281.19 


281.10 


+30 


281.01 


280.92 


28085 


280.76 


280.66 


280.56 


280.45 


280.35 


280.24 


280.12 


+40 


279.97 


279.81 


279.67 


279.53 


279.37 


279.20 


279.02 


278.83 


278.65 


278.46 


+50 


278.26 


27803 


277.78 


277.50 


277.20 


276.90 


276.60 


276 30 


276.00 


275.71 


+60 


275.36 


275.00 


274.65 


274.28 


273.90 


273.47 


273.04 


272.57 


272.07 


271.54 


+70 


270.97 


270.30 


269.65 


268.80 


267.90 


267.00 


266.10 


265.19 


264.25 


263.25 


+80 


262.18 


261.00 


259.80 


258.60 


257.15 


255.50 


253.71 


250.00 






+87.8 


240.30 


Critical point 



TABLE 78. Heat of Vaporization of Carbon Dioxide in B. t. u. lib. 
(Data of Plank and Kuprianoff) 



-699 


149.6 


Triple point 


-60 


145.8 


146.2 


146.6 


146.9 


147.3 


147.7 


148.1 


148.5 


148.9 


149.3 


-50 


141.9 


142.3 


142.6 


143.0 


143.4 


143.8 


144.2 


144.6 


145.0 


145.4 


-40 


137.8 


138.2 


138.6 


139.0 


139.4 


139.8 


140.2 


140.6 


141.1 


141.5 


-30 


133.7 


134.1 


134.5 


135.0 


135.4 


135.8 


136.2 


136.6 


137.0 


137.4 


-20 


129.5 


129.9 


130.3 


130.8 


131.2 


131.7 


132.1 


132.5 


132.9 


133.3 


-10 


124.9 


125.4 


125.8 


126.3 


126.8 


127.2 


127.7 


128.2 


128.6 


129.0 


- 


120.0 


120.5 


121.0 


121.5 


122.0 


122.5 


123.0 


123.5 


124.0 


124.5 


+ o 


120.0 


119.5 


119.0 


118.5 


118.0 


117.5 


117.0 


116.5 


116.0 


115.4 


+ 10 


114.9 


114.3 


113.7 


113.1 


112.5 


112.0 


111.4 


110.8 


110.2 


109.6 


+20 


109.0 


108.4 


107.7 


107.0 


106.4 


105.7 


105.0 


104.4 


103.7 


103.1 


+30 


102.4 


101.7 


101.0 


100.3 


99.60 


98.90 


98.15 


97.40 


96.60 


95.82 


+40 


95.04 


94.23 


93.43 


92.63 


91.83 


90.93 


90.13 


89.28 


88.40 


87.50 


+ 50 


86.56 


85.61 


84.65 


83.68 


82.70 


81.70 


80.70 


79.68 


78.60 


77.53 


+60 


76.45 


75.55 


74.40 


73.23 


72.00 


70.73 


69.44 


68.13 


66.78 


65.38 


+70 


63.90 


62.25 


60.55 


58.80 


57.00 


55.20 


53.30 


51.35 


49.40 


47.40 


+80 


45.30 


43.00 


40.50 


37.70 


34.40 


30.85 


27.09 


20.00 






+87.8 


00.00 


Critical point 



APPENDIX 

TABLE 79. Entropy of Saturated Liquid Carbon Dioxide 
(Data of Plank and Kuprianoff) 



281 



p. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


-69.9 


.8885 


Triple point 


-60 


.8997 


.8986 


.8975 


.8964 


.8952 


.8940 


.8928 


.8917 


.8906 


.8895 


-50 


.9109 


.9098 


.9087 


.9076 


.9065 


.9054 


.904* 


.9032 


.9020 


.9009 


-40 


.9218 


.9208 


.9197 


.9186 


.9175 


.9164 


.9153 


.9142 


.9131 


.9120 


-30 


.9324 


.9314 


.9303 


.9293 


.9283 


.9272 


.9261 


.9250 


.9240 


.9229 


-20 


.9428 


.9418 


.9408 


.9397 


.9386 


.9376 


.9365 


.9354 


.9344 


.9334 


-10 


.9532 


.9521 


.9511 


.9501 


.0490 


.9480 


.9470 


.9459 


.9449 


.9439 


- 


.9637 


.9626 


.9615 


.9605 


.9594 


.9584 


.9574 


.9564 


.9553 


.9542 


+ 


.9637 


.9648 


.9659 


.9669 


.9680 


.9690 


.9701 


.9711 


.9721 


.9732 


+ 10 


.9743 


.9754 


.9765 


.9776 


.9787 


.9798 


.9809 


.9820 


.9831 


.9842 


+20 


.9854 


.9856 


.9878 


.9890 


.9902 


.9913 


.9925 


.9936 


.9942 


.9959 


+30 


.9971 


.9982 


.9996* 


1.0007 


1.0018 


1.0030 


1.0041 


1.0053 


1.0066 


1.0078 


+40 


1.0090 


10103 


1.0116 


1.0128 


1.0140 


1.0152 


1.0165 


1.0177 


1.0190 


1.0204 


+50 


1.0218 


1.0231 


1.0244 


1.0257 


1.0270 


1.0284 


1.0298 


1.0312 


1.0326 


1.0340 


+60 


1.0354 


1.0368 


1.0382 


1.0396 


1.0410 


1.0424 


1.0439 


1.0454 


1.0468 


1.0484 


+70 


1.0500 


1.0517 


1.0534 


1.0551 


1.0569 


1.0588 


1.0608 


1.0628 


1.0648 


1.0667 


+80 


1.0687 


1.0710 


1.0732 


1.0756 


1.0782 


1.0817 


1.0854 


1.0914 






+87.8 


1.1098 


Critical point 


*NoiE : The data of Plank and Kup 


nanoff i 


ire based on a value of 1.00000 Clausius at 32 F. a smooth 


curve, 


however, gives a value of .9996 Clausius at this temperature and this value is therefore used 


in this 


table. 























TABLE SO. Entropy of Saturated Carbon Dioxide Vapor 
(Data of Plank and Kuprianoff) 



op 





1 2 


3 


4 


5 


6 


7 


8 


9 


-699 


1.2724 


Triple point. 
















-60 


1.2647 


1.2655 1.2662 1.2670 


1.2678 


1.2685 


1.2693 


1.2700 


1.2709 


1.2717 


-50 


1 2572 


1.2579 1.2586 1.2593 


1.2601 


1.2609 


1.2616 


1.2624 


1.2631 


1.2639 


-40 


1.2503 


1.2509 1.2515 1 


.2522 


1.2529 


1 2536 


1.2543 


1.2550 


1.2557 


1.2565 


-30 


1.2437 


1.2443 


2450 1 2456 


1.2463 


1 2469 


1.2476 


1.2483 


1.2489 


1.2496 


-20 


1.2373 


1.2379 


.2385 1.2392 


1.2398 


1.2405 


1.2411 


1.2417 


12423 


1.2430 


-10 


1.2309 


1.2315 


.2322 1.2328 


1.2335 


1.2341 


1.2348 


1.2354 


1.2360 


1.2367 


- 


1.2248 


1.2254 


.2260 1.2266 


1.2272 


1.2279 


1.2285 


1 2291 


1.2297 


1.2303 


+ 


1.2248 


1 2242 


.2236 1.2230 


12224 


12218 


1.2212 


1.2206 


1.2200 


1.2194 


+ 10 


1.2188 


1.2182 


.2176 1 


.2170 


1.2163 


1.2157 


1.2151 


1.2145 


1.2139 


1.2133 


+20 


1.2127 


1.2121 


.2115 


.2109 


1.2103 


1.2097 


1.2091 


1.2085 


1.2079 


1.2073 


+30 


1.2067 


1.2061 


2055 


.2048 


1.2041 


1.2033 


1.2025 


1.2017 


1.2009 


1.2001 


+40 


1.1993 


1.1985 


.1977 


.1971 


1.1963 


.1956 


1.1948 


1.1940 


1.1933 


1.1925 


+ 50 


1.1917 


1.1908 


.1899 


.1890 


1.1882 


.1853 


1.1863 


1.1854 


1.1945 


1.1835 


+60 


1.1824 


1.1814 


.1803 


.1792 


1.1781 


.1770 


1.1758 


1.1746 


1.1734 


1.1718 


+70 


1.1703 


1.1688 


.1673 


1658 


1.1641 


.1623 


1.1604 


1.1585 


1.1565 


1.1545 


+80 


1.1523 


1.1500 


.1476 ] 


L.1452 


1.1423 


.1390 


1.1351 


1.1280 






+87.8 


1.1098 


Critical point. 

















SATURATED SOLID AND VAPOR 

TABLE 81. Vapor Pressure of Solid Carbon Dioxide in Ibs./in* (absolute) 
(Data of Plank and Kuprianoff) 



op 





1 


2 


3 


4 


5 


6 


7 


8 


9 


69.9 


75.08 


Triple point. 


70 


74.90 


7210 


69.40 


66.75 


64.25 


61.75 


59.44 


57.20 


55.00 


52.80 


80 


50.70 


4875 


46.85 


45.00 


43.30 


41.67 


40.05 


38.50 


37.00 


35.50 


90 


34.05 


32.60 


31.20 


29.90 


28.72 


27.63 


26.54 


25.45 


24.40 


23.35 


100 


2234 


21.35 


20.40 


19.48 


1859 


17.80 


17.00 


16.30 


15.61 


14.92 


110 


14.22 


13.60 


13.00 


12.34 


11.76 


11.20 


10.67 


10.18 


970 


9.27 


120 


8.85 


8.46 


8.08 


7.70 


7.33 


6.98 


6.63 


6.29 


5.97 


5.67 


130 


5.39 


5.11 


4.85 


4.61 


4.38 


4.16 


3.95 


3.75 


3.55 


3.36 


140 


3.19 


3.03 


2.87 


2.72 


2.57 


2.43 


2.28 


2.14 


2.01 





282 CARBON DIOXIDE 

TABLE 82. Specific Volume of Solid Carbon Dioxide in cu. ft. lib. 
(Data of Maass and Barnes) 



69.9 
70 
80 
90 
100 
110 
120 
130 
140 


0.01059 
0.01059 
.01049 
.01040 
.01032 
.01024 
.01018 
.01012 
.01007 


Triple point. 
0.01058 0.01057 
.01048 .01047 
.01039 .01038 
.01031 .01030 
.01024 .01023 
.01017 .01017 
.01012 .01011 
.01007 .01006 


0.01056 
.01046 
.01037 
.01030 
.01022 
.01016 
.01011 
.01006 


0.01055 
.01045 
.01036 
.01029 
.01022 
.01015 
.01010 
.01006 


0.01054 
.01044 
.01036 
.01028 
.01021 
.01015 
.01009 
.01005 


0.01053 
.01043 
.01035 
.01027 
.01020 
.01014 
.01009 
.01005 


0.01052 
.01042 
.01034 
.01026 
.01020 
.01014 
.01008 
.01004 


0.01051 
.01041 
.01033 
.01026 
.01019 
.01013 
.01008 
.01004 


0.01050 
.01040 
.01032 
.01025 
.01018 
.01013 
.10007 
.01004 



TABLE 83. Specific Volume of Saturated Carbon Dioxide Vapor over Solid in cu. ft. lib. 
(Data of Plank and Kuprianoff ) 



69.9 
70 


1.16 
1.17 


Triple point. 
1.21 1.25 


1.30 


1.35 


1.40 


1.46 


1.51 


1.56 


1.63 


80 


1.70 


1.76 


1.83 


1.91 


1.99 


2.07 


2.15 


2.24 


2.33 


2.42 


90 


2.52 


2.63 


2.74 


2.85 


2.97 


3.09 


3.22 


3.36 


3.50 


3.65 


100 


3.80 


3.97 


4.14 


4.32 


4.52 


4.72 


4.93 


5.25 


6.37 


5.60 


110 


5.85 


6.10 


6.37 


6.65 


6.95 


7.27 


7.60 


7.97 


8.34 


8.73 


120 


9.13 


9.58 


10.04 


10.51 


11.02 


11.56 


12.12 


12.70 


13.32 


14.00 


130 


14.74 


15.48 


16.20 


16.98 


17.80 


18.70 


19.70 


20.78 


2196 


23.11 


140 


24.50 


25.95 


27.50 


29.10 


30.75 


32.40 


34.10 


35.80 


37.42 





TABLE 84. Density of Solid Carbon Dioxide in Ib. cu./ft. 
(Data of Maass and Barnes) 



69.9 


94.42 


Triple point. 


70 


94.43 


94.53 


94.63 


94.73 


94.83 


94.92 


95.01 


9510 


95.19 


95.28 


80 


95.37 


95.46 


95.55 


95.63 


96.72 


95.80 


95.88 


95.97 


96.05 


96.13 


90 


96.21 


96.29 


96.37 


96.44 


96.52 


96.59 


96.66 


96.74 


96.82 


96.89 


100 


96.96 


97.03 


97.10 


97.17 


97.24 


97.31 


97.38 


97.44 


97.51 


97.57 


110 


97.64 


97.70 


97.77 


97.83 


97.89 


97.95 


98.01 


98.07 


98.13 


98.19 


120 


98.25 


98.31 


98.36 


98.41 


98.47 


98.52 


98.57 


98.62 


98.67 


98.72 


130 


98.77 


98.82 


98.87 


98.92 


98.96 


99.01 


99.06 


99.10 


99.14 


99.19 


140 


99.23 


99.27 


99.32 


99.36 


99.41 


99.45 


99.49 


99.54 


99.58 


99.62 


TABLE 85. Density of Saturated Vapor over Solid Carbon Dioxide in Ib./cu. ft. 


op 





1 


2 


3 


4 


5 


6 


7 


8 


9 


69.9 


0.8640 


Triple point. 


70 


0.8600 


0.8250 


0.7920 


0.7625 


0.7360 


0.7100 


0.6848 


0.6600 


0.6350 0.6100 


80 


.5865 


.5630 


.5425 


.5220 


.5020 


.4832 


.4650 


.4480 


.4310 


.4130 


90 


.3960 


.3805 


.3655 


.3510 


.3365 


.3210 


.3060 


.2930 


.2815 


.2710 


100 


.2605 


.2505 


.2410 


.2316 


.2225 


.2130 


.2045 


.1960 


.1875 


.1795 


110 


.1710 


.1635 


.1567 


.1500 


.1435 


.1372 


.1312 


.1252 


.1297 


.1145 


120 


.1093 


.1044 


.0995 


.0950 


.0905 


.0862 


.0822 


.0782 


.0745 


.0710 


130 


.0679 


.0647 


.0615 


.0585 


.0657 


.0529 


.0504 


.0479 


.0455 


.0433 


140 


.0410 


.0390 


.0372 


.0354 


.0337 


.0320 


.0303 


.0285 


.0267 


.0250 



TABLE 86. Enthalpy of Solid Carbon Dioxide in B. t. ujlb. 
(Data of Plank and Kuprianoff) 



69.9 
70 
80 
90 
100 
110 
120 
130 
140 


45.38 
45.22 
40.87 
36.69 
33.23 
30.11 
27.23 
24.46 
21.75 


Triple 
44.82 
40.42 
36.32 
32.91 
29.82 
26.96 
24.18 
21.48 


point. 
44.40 
39.98 
35.96 
32.59 
29.53 
26.67 
23.91 
21.21 


43.97 
39.54 
35.61 
32.27 
29.24 
26.39 
23.64 
20.94 


43.54 
39.11 
35.26 
31.96 
28.96 
26.11 
23.37 
20.67 


43.11 
38.68 
34.91 
31.65 
28.66 
25.83 
23.10 
20.40 


42.68 
38.28 
34.57 
31.34 
28.37 
25.55 
22.82 
20.13 


42.22 
37.88 
34.23 
31.03 
28.08 
25.27 
22.55 
19.86 


41.77 
37.48 
33.89 
30.72 
27.79 
24.99 
22.28 
19.59 


41.32 
37.08 
33.55 
30.41 
27.51 
24.72 
22.01 
19.32 



APPENDIX 

TABLE 87. Enthalpy of Saturated Carbon Dioxide Vapor in B. t. u./lb. 
(Data of Plank and Kuprianoff,) 



283 



F. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


69.9 


279.16 


Triple point. 


70 


279.16 


279.15 


279.15 


279.14 


279.13 


279.12 


279.11 


279.10 


279.07 


279.04 


80 


279.00 


278.96 


278.92 


278.87 


278.82 


278.77 


278.71 


278.65 


278.59 


278.52 


90 


278.45 


278.38 


278.30 


278.22 


278.14 


278.06 


277.98 


277.89 


277.80 


277.71 


100 


277.62 


277.52 


277.42 


277.31 


277.21 


277.10 


276.99 


276.88 


276.77 


276.65 


110 


276.53 


276.41 


276.29 


276.16 


276.04 


275.91 


275.78 


275.65 


275.53 


275.40 


120 


275.28 


275.15 


275.02 


274.88 


274.74 


274.51 


274.47 


274.34 


274.21 


274.07 


130 


273.93 


273.79 


273.65 


273.61 


273.37 


273.23 


273.08 


272.93 


272.78 


272.63 


140 


272.48 


272.33 


272.18 


272.03 


271.87 


271.70 


271.53 


271.35 


271.17 


270.98 



TABLE 88. Heat of Sublimation of Solid Carbon Dioxide in B. /. u./lb. 
(Data of Plank and Kuprianoff) 



op 





1 


2 


3 


4 


5 


6 


7 


8 


9 


69.9 


233.78 


Triple point. 


70 


233.82 


234.26 


234.70 


235.14 


235.58 


236.02 


236.43 


236.86 


237.28 


237.70 


80 


238.12 


238.52 


238.91 


239.30 


239.69 


240.08 


240.45 


240.80 


241.16 


241.48 


90 


241.79 


242.08 


242.36 


242.63 


242.88 


243.14 


243.40 


243.66 


243.90 


244.14 


100 


244.38 


244.60 


244.82 


245.03 


245.24 


245.43 


245.63 


245.83 


246.01 


246.19 


110 


246.38 


246.57 


246.74 


246.92 


247.08 


247.25 


247.41 


247.57 


247.73 


247.88 


120 


248.03 


248.18 


248.32 


248.46 


248.60 


248.74 


248.88 


249.01 


249.15 


249.28 


130 


249.42 


249.55 


249.68 


249.81 


249.93 


250.05 


250.17 


250.29 


250.42 


250.54 


140 


250.65 


250.77 


250.89 


251.00 


251.12 


251.24 


251.35 


251.47 


251.58 


251.69 


TABLE 89. Entropy of Solid Carbon Dioxide 








(Data 


of Plank and 


Kuprianoff) 


op 





1 


2 


3 


4 


5 


6 


7 


8 


9 


69.9 


0.6725 


Triple point. 


70 


0.6724 


0.6713 


0.6702 


0.6690 


0.6679 


0.6667 


0.6655 


0.6643 


0.6631 


0.6619 


80 


0.6608 


0.6596 


0.6584 


0.6573 


0.6562 


0.6551 


0.6540 


0.6530 


0.6519 


0.6509 


90 


0.6498 


0.6488 


0.6478 


0.6469 


0.6459 


0.6450 


0.6440 


0.6431 


0.6421 


0.6412 


100 


0.6403 


0.6394 


0.6385 


0.6376 


0.6367 


0.6358 


0.6350 


0.6341 


0.6332 


0.6323 


110 


0.6314 


0.6307 


0.6299 


0.6290 


0.6282 


0.6274 


0.6265 


0.6257 


0.6248 


0.6240 


120 


0.6232 


0.6224 


0.6216 


0.6208 


0.6199 


0.6191 


0.6183 


0.6175 


0.6167 


0.6158 


130 


0.6150 


0.6141 


0.6133 


0.6124 


0.6116 


0.6108 


0.6099 


0.6091 


0.6082 


0.6074 


140 


0.6065 


0.6057 


0.6048 


0.6039 


0.6031 


0.6022 


0.6013 


0.6004 


0.5996 


0.5987 



TABLE 90. Entropy of Saturated Carbon Dioxide Vapor 
(Data of Plank and Kuprianoff) 



69.9 
70 
80 
90 
100 
110 
120 
130 
140 


1.2724 
1.2726 
1.2883 
1.3040 
1.3199 
1.3363 
1.3536 
1.3718 
1.3909 


Triple point. 
1.2741 1.2757 
1.2899 1.2914 
1.3056 1.3071 
1.3215 1.3231 
1.3380 1.3398 
1.3554 1.3572 
1.3736 1.3755 
1.3929 1.3950 


1.2772 
1.2930 
1.3087 
1.3248 
1.3415 
1.3590 
1.3773 
1.3970 


1.2788 
1.2945 
1.3103 
1.3264 
1.3431 
1.3608 
1.3792 
1.3990 


1.2803 
1.2960 
1.3120 
1.3280 
1.3448 
1.3627 
1.3811 
1.4010 


1.2819 
1.2976 
1.3136 
1.3296 
1.3467 
1.3645 
1.3831 
1.4030 


1.2835 
1.2992 
1.3151 
1.3313 
1.3484 
1.3663 
1.3850 
1.4050 


1.2851 
1.3008 
1.3167 
1.3330 
1.3501 
1.3681 
1.3870 
1.4070 


1.2867 
1.3024 
1.3183 
1.3346 
1.3519 
1.3700 
1.3889 
1.4090 



Author Index 



Addams, R., 16 

Alexjcv, D., 50 

Allen, E. T., 24 

Allmand, A. J., 89 

Altmann, A., 129 

Amagat, E. H., 38, 50, 52, 54, 56, 59 

Anibro, 77 

Andrews, J. W., 59, 69 

Arago, 81 

Armct, H, 144 

Arnt, 133 

Auerbach, E. B., 112 

Augustine, C. E., 148 

Austin, L., 65 

Austin, R., 162, 163 

Back, E. A., 144 

Backus, A. A., 185 

Bacon, R. F., 265 

Bacquercl, 108 

Bagnal, 1). J. T., 140 

Bahr, Herbert, 132 

Bangham, D. II , 91 

Barnes, W. II., 40, 57, 68, 69, 70 

Baum, Hugo, 18 

Bcattie, J. A., 57 

Bchn, U., 38, 39, 69 

Behnken, H. E., 80 

Behrens, E. A., 177 

Behrens, H., 134 

Behrens, J., 177 

Beins, H., 17, 18 

Beins, T. F., 18 

Belcher, D., 118, 119 

Bell, 59 

Benedict, F. G., 21 

Benton, A. F., 90 

Bergman, Tobern, 13 

Berl, E., 126 

Bernstein, R., 142, 1-13 

Bcrthelot, D., 40 

Berzelius, J. J., 35 

Riot, 81 

Birnbaum, L., 140 

Bjerrum, Niels, 64 

Black, C. A., 135 

Black, Joseph, 12 

Blake, R. E., 20 

Blaserna, P., 41 

Rleekrode, L., 35, 39. 81 

Bodlander, G., 118, 119 

Bodmer, 133 

Bohr, C, 95, 101, 104, 106 

Bolas, I. B. D., 137 



Borneman, 137, 138 
Bosworth, A. W., 254 
Bosworth, R. C, 91 
Boudouard, 133 
Bouquet, M., 26 
Boussingault, M , 24 
Bradley, W. P., 59 
Bratley, C. O., 260 
Bray, U. B., 154 
Breitenbach, P., 43 
Brewster, David, 29 
Bridgeman, O. C, 57, 61 
Bridgcman, P. W., 60, 71 
Brier, Henry, 198 
Brinkman, R, 117 
Brinkinann, 59 
Brooks, Chas., 239, 2(>0, 261 
Brown, A. W., 59 
Brown, E. W., 139 
Brown, H. T., 20 
Buch, K., 119, 152 
Buchanan, J. G., 120, 121 
Buchanan, J. Y., 23 
Biichncr, E. IT., 109 
Buckcndahl, O., 41 
Bunsen, R., 82 
Burnett, E. S., 72, 74, 75 
Burragc, L. I., 89 
Bush, R. J., 265 
Butler, 29 

Buytendyke, F. J. J., 117 
Byke, H. T., 119 

Cailletet, L. P., 59, 108 
Cambier, R , 20 
Cameron, F. K., 121, 128 
Camus, 255 

Carbide and Carbon Chemicals Corpo- 
ration, 152 
Cardoso, 59 
Carlberg, J., 118 
Carlson, 106 
Carr, A. R., 268 
Carticr, P., 161 
Castelli, G., 26 
Cavendish, H., 12 
Chadwick, S., 131 
Chamberlin, T. C., 22, 33 
Chaplin, R., 89, 92 
Chapman, D. L., 131 
Chappuis, J., 53, 59, 68, 81 
Chopin, Marcel, 65 
Christoff, A., 97, 101, 103 
Church, 239 



285 



286 



AUTHOR INDEX 



Clark, F. W., 22 
Clark, K. G., 135 
Clark, W., 162, 163 
Cobb, J. W., 133 
Cook, W. R., 41 
Cooke, J. P., 35 
Cooley, J. S., 239, 260 
Cooper, D. LeB., 40 
Cormak, W., 118 
Coryllos, P. N., 140 
Cotton, R. T., 144 
Couder, A., 177 
Cox, J. H., 144 
Coyne, F. P., 261 
Crafts, J. M., 35 
Crawford, F. M., 189 
Crookes, W., 41 
Cross, R. J., 267 
Croullebois, 81 
Cummings, M. B., 136 

D'Andreef, M. E., 37 
David, E. V., 240 
Davis, G. H. B. f 160, 161 
Davis, R. O. E., 135 
Davis, W. A., 128 
De Hecn, 59 
Dent, F. J., 132, 133 
dc Saussure, H. B., 19 
cle Thierry, M., 20 
Deuvil, C. O., 235 
Dcwar, J., 39, 50, 59, 108 
Dewey, M. A., 131 
Dietrich, E., 34 
Dittmar, W., 22. 23 
Dixon, J. K., 89 
Donath, E., 69, 70 
Donny, F., 15 
Dolter, C., 108 
Dorsman, 59 
Drake, L. C., 90 
Drane, H. D. H., 166 
Drenteln, 35 
Drinker, C. K., 139, 140 
Drucker, Carl, 91 
Dulong, P. L., 35, 81 
Dunn, F. L., 243 

Eastman, E. D., 133, 134 
Edwards, J. P., 47, 50 
Eglin, J. M., 42 
Ehrenberg, P., 137 
Elworthy, H. S., 193, 198, 232 
Emich, F., 34 
Erickson, W. R., 39, 110 
Escombe, F., 20 
Espenmiiller, 177 
Eucken, A., 66, 69, 70, 115 
Exessner, C, 266 
Exncr, E., 35 

Fabius, 59 
Fakhoury. N., 91 



Faraday, M., 14, 15, 16 

Farine, A., 184 

Farr, W. S., 240 

Favre, P. A., 69 

Findlay, A., 101, 103, 104, 106, 107, 108 

Fischer, H., 137 

Flatnmarion, 25 

Fleck, W., 144 

Florentine, D., 20 

Foote. H. W., 89 

Forbes, 27 

Ford, J. M., 201 

Fox, C. J. J., 23 

Fraenkel, W., 133, 134 

Franck, H. H., 126 

Frear, G. L., 123, 124 

Fremy, 89 

Fritzschc, A., 155, 157, 160, 170 

Fuwa, T, 47 

Gabriel, C. L. f 189 

Gaddy, V. L, 135 

Geffcken, G., 101 

Gering, A., 137 

Gcrlach, 138 

Giebenhain, H., 89, 93, 94 

Gillette, E. P., 180 

Good, A. C., 268 

Goodman, J. B., 131 

Goosmann, J. C, 77, 149, 166, 184, 198, 

246, 247 
Gore, G., 108 



Graftiau, J., 20 
Graham, T., 41, 



46 



v_ji auciiii, J. ., ^A, TVI 

Green, A. A., 119 
Greene, O. V., 242 
Greenhorne, T. R., 267 
Gruschke, 81 
Griitzner, H. G., 115 
Guye, P. A., 34, 35 

Hackspill, I., 177 

Haehnel, O, 20, 117, 122, 128 

Haggard, H. W., 140 

Hale, C. F., 59 

Hales, 12 

Hamberg, A., 23 

Hamilton, 265 

Hannay, J. B., 82, 108 

Hannen, F., 46 

Hapke, 28 

Hartley, 29 

Harvey, H. W., 119 

Hasse, H. R., 41 

Hautefeuille, 59 

Hayhurst, E. R., 140 

Hazelhoff, E. H., 144 

Heath, W. P., 96, 181 

Hein, Paul, 59, 60 

Heirich, C., 152 

Heller, E., 139 

Hempel, W., 113 

Henderson, F. Y., 137 



AUTHOR INDEX 



287 



Henderson, P. D., 198 
Henderson, Y., 140 
Hene, W., 89 
Henning, F., 63, 65 
Herb, C. O., 240 
Hervy, M., 15 
Heusler, 27 
Heydemann, F., 137 
Heyerdahl, P. M., 265 
Hill. Walter, 16, 252 
Hirano, H., 88 
Hirschefeld, A., 142 
Hodgman, C. D., 97 
Hoffman, Fr., 11 
Hofsass, M., 41 
Holborn, L., 65 
Homfray, Ida F., 86 
Houlton, B. F., 246 
Howell, O. R., 108 
Hunt, F. B., 77 
Hunt, T. S., 32 

laccard, Paul, 137 
Irvine, R., 121, 2r>7 
Ishida, T., 42 

Jacobscn, O., 23 

acoby, 133 

amine, 81 

iinecke, E., 135 

anert, Heinz, 137 
Jaquerod, A., 34, 40 
Jarry, 58 

Jeans, J. H., 40, 41 
Jenkin, C. F.. 39, 52, 67, 71, 72, 75 
Johnson, F. M. G., 90 
Johnson, H. B. f 239, 260 
Johnston, J., 122, 123, 124, 128, 154 
Jones, C. H., 136 

Jones, C. L., 205, 230, 238, 258, 267 
Jones, G. W., 145 
Josephson, W. S., 204 
Turjew, W. J., 90 
Just, G., 104, 105 

Kalbercr, W., 84, 85, 88, 90, 94 

Kammerlingh-Onnes, H., 56, 61, 63 

Kandler, R., 119 

Kauko, Y., 118, 119 

Keesom, W. H., 52, 59 

Kelly, E. M., 124 

Kelvin, 54, 76 

Kendall, J., 118 

Kennedy, H. T., 59 

Kennedy, R. E., 145 

Kenrick, F. B., 108 

Kcster, F. E., 71 

Kettler, 81 

Keyes, F. G., 68, 79, 80 

Kidd, F., 260 

Kieffer, R., 84 

Killeffer, D. H., 189, 242, 261 



Killiches, W., 139 
Kimetowicz, E., 142 
King, C. W., 239 
King, F. E., 65 
King, G., 106, 107 
Kinney, A. W., 68 
Kirkwood, J. G., 79, 80 
Klar, R., 91 

Klemenc, A., 42, 43, 135 
Kline, W. D., 123, 124, 129 
Kneser, II. O., 41 
Knibbs, N. V. S., 180 
Knofel, J., 126 
Knox, 118 
Koch, 81 
Konig, 28 
Krase, H. J., 135 
Krase, N. W., 131 
Kratz, H., 88, 90, 92 
Kreisinger, H., 148 
Krichevskil, I. R., 92 
Krogh, A., 21, 22 

Kuenen, J. P., 58, 59, 60, 63, 69, 70 
Kundt, A., 41 
Kuester, H., 132 
Kunerth, William, 105 
Kunheim, Hugo, 18 

Kuprianoff, J., 35, 40, 56, 57, 59, 61, 69, 
70, 75, 76, 77, 201, 207, 208, 209 

Laine, E., 21 

Landolt, H., 39 

Lange, N. A., 97 

Lanning, C. E., 89 

Laplace, P. S., 14 

Lasalle, L. J., 42 

Laughton, W. M., 244 

Lavoisier, A. L., 14 

Lea, C. H., 261 

Leake, C. D., 141 

Leduc, A, 35, 53, 65, 66 

Legendre, R., 21 

Lemarchands, M., 134 

Letts, E. A., 20 

Lewis, G. N., 64 

Lewis, W. K, 148, 158, 265 

Libavius, L., 12 

Lightfoot, 198 

Linde, C., 198 

Linde, F., 79 

Liversidge, A., 80 

Loomis, A. L., 95 

Lortie, L., 161 

Loschmidt, J., 45 

Loudon, A., 25 

Lowenstein, L., 40, 64 

Lowry, H. H., 39, 90, 110 

Lubarsch, 104 

Lubbcrger, W., 127 

Luber, A., 117 

Luerssen, G. V., 242 

Luhmann, 151, 255 

Lundegardh, H., 21, 30, 31, 137 



288 



AUTHOR IN DUX 



Maass, O., 40, 57, 68, 69, 70, 114, 118, 

120 

McAclams, W. H., 148, 158 
McBain, J. W., 115 
McBride, D, 12 
McCoy, H. N., 154 
McCrea, E. F., 141 
Maclnnes, D. A., 118, 119 
Macintire, H. J., 201, 225, 248 
Mackenzie, J. E., 45, 101 
Macy, F., 20 
Maeda, Tsutomu, 133 
Magnus, A., 53, 84, 88, 89, 90, 91, 92, 

93, 94 

Maiuri, G., 220 
Marchal, G., 82 
Marchand, R. F., 35 
Mareska, J., 15 
Margaria, R., 119 
Mark, H., 80, 84, 90, 94 
Marsh, F. W., 30 
Martin, J. W., 28 
Martin, J. W., Jr., 207, 238 
Mascart, 81 
Matalskii, V., 50 
Mathews, J. H., 160, 167 
Mathias, R., 68 
Matignon, C, 82 
Mattcucci, C., 46 
Maxwell, J. C, 41, 45 
Mayer, 133 
Mellor, J. W., 19, 64 
Melville, II. W., 45 
Menzel, II., 119 
Meppen, B., 126 
Metschl, John, 108 
Meyer, G., 133 
Meyer, O. E., 42 
Meyer, Victor, 64 
Meyers, C. H., 58, 59, 60, 63 
Meyers, S. L., 268 
Miller, E. V., 239, 260, 261 
Millring, E. R., 265 
Minor, H. R., 267 
Minor, J. C, 189 
Mohr, F., 35 
Mook, H. W., 117 
Mook, P. V., 239, 260 
Moore, M. B., 120, 121 
Moore, W. C, 185 
Moran, T., 261 
Morgan, O. M., 114, 118, 120 
Morgan, S. O., 90 
Morse, S., 265 
Moss, E. T.., 21 
Moulton, R. S., 258 
Miillcr, E., 117, 126, 127 
Miiller, O., 104 
Munro, L. A., 90 
Miintz, A., 21 

Natterer, F., 23 
Natterer, Johann, 16 



Nernst, 64 
Neumann, B., 266 
Newell, I. L., 124 
Newth, G. S., 193 
Nicol, E. W. L., 147 
Nikitin, N. J., 90 
Niklas, II., 138 
Nitardy, F. W., 265 
Nooth, 14 

Onnes, 59 
Osburn, M. R., 144 
Ovitz, F. K., 148 
Owens, A. E., 82 

Parr, S. W., 35 

Partington, J. R-, 66 

Patrick, W. A., 82 

Pcgna, E. G., 219 

Perrcau, 81 

Perrot, F. L, 34, 40 

Peterman, A., 20 

Peters, K M 132 

Pfeiffer, E., 118 

Phillips, P., 43 

Pickering, S. F., 47, 50 

Pier, M., 65 

Pierre, L, 184 

Plank, R., 35, 56, 57, 59, 61, 69, 70, 75, 

76, 77, 201 
PU'ischl, 16 
Pliny, 11 
Pohlaml, E., 80 
Poscjpal, V., 81 
Pratt, J. H., 248 
Preston, W. C., 82 
Pridcau, E. 15. R., 119 
Priestley, Joseph, 12, 13 
Printza, A., 34 
Pyc, D. R., 67, 68, 71, 75 

Quinn, 1C. L., 26, 77, 79, 109, 177 

Radloff, M., 140 
Rahlfs, E., 135 
Raikow, P. N., 128 
Ranisbottom, J. E., 131 
Ranc, A., 137 
Randall, M., 64, 132 
Raper, H. S., 141 
Raydt, W., 17, 18 
Rayleigh, Lord, 35, 40 
Rector, T. M., 264 
Regnault, H. V., 35, 53, 68 
Reich, G. T., 186, 193 
Reinan, E., 137 
Reinau, E. H., 21, 138 
Reiset, J. A., 20 
Remi, W., 42, 43 
Remy, H., 89 
Rentschler, 81 
Reycrson, L. H., 89 
Rhead, 133 



AUTHOR INDEX 



289 



Richardson, L. B., 87, 88, 91 
Riede, W., 138 
Ricdcl, F., 137 
Riegger, H., 79 
Riou, P., 160, 161 
Rittcner, A., 126 
Riviere, C., 81 
Robinson, J., 41 
Robinson, P., 133, 134 
Robinson, W. O., 121, 128 
Robson, W. G., 58, 60, 63, 69, 70 
Roman, H. L., 134 
Rommcnholler, C. G., 18, 27 
Roscoc, H. S., 46 
Roth, Walter, 46 
Russ, J. M., 144 

Salisbury, R. D., 33 

Salmony, A., 217 

Sameshinia, J., 85 

Sander, W., 96, 106 

Scharrer, K., 138 

Schcermesser, F., 81 

Scheffer, F. E. C, 133 

Schmidt, 45 

Schmidt, W., 137 

Schorizer, Rudolph, 29 

Schott, A., 142 

Schraube, 133 

Schulte, E., Ill 

Schultc-Overbeck. 137 

Schultz, B., 21, 23 

Schultzig, R., 140 

Schuster, C., 85 

Schiitz, G. A., 213 

Schwalbe, B., 39 

Scott, E., 140 

Seidel, J. f 113, 138 

Sctschcnow, 97, 101, 103 

Sharp, P. F., 264 

Shaughnessy, J., 140 

Sheldon, R F., 141 

Shen, B., 101, 103, 104 

Shiffler, W. IT., 132 

Shorthosc, 72, 75 

Shutt, F. T., 264 

Sieve rs, E. G., 29 

Sicverts, A., 155, 157, 160, 170 

Small, T., 137 

Smith, C. J., 42 

Smith, E. C, 261 

Smith, R. H., 58 

Snipischski, K., 133, 134 

Sorby, 29 

Spoehr, H. A., 22, 23, 31 

Srikantan, B. S., 132 

Sutherland, W., 42, 43 

Stefan, J., 45 

Stern, Otto, 104, 106 

Steinitzer, F., 48 

Stewart, R. T., 190 

Stickney, A. B., 196, 203 

Stork, A., 63 



Strobel, A., 138 
Stroheckcr, E. R., 115, 117 
Stuckcrt, 81 
Strutt, R. J., 35 
Stumper, R., 129 
Sturckc, 254 
Suprucnko, A., 31 
Swearingen, L. E., 89 

Tammann, G., 60 
Tankard, A. R., 140 
Tennant, Smithson, 14 
Tcrada, K., 129 
Terres, E. f -134 
Thiel, A., Ill, 115 
Thicscn, 69 
Thilorier, M., 15, 35 
Thornton, N. C., 260, 261 
Tichborne, C. R. C., 193 
Tiepolt, P., 145 
Tillman, 125 
Titoff, Alexander, 87 
Tomkins, R. G., 261 
Tomlinson, G. H., 154 
Toplcy, B., 133 
Torneo, H., 23 
Trout, S. A., 260 

Ullman, 1?., 190 
Usher, F. L., 103 

Valley, G., 260 

Vandecaveye, S. C, 31, 138 

van der Waal, 54 

Van Dusen, M. S., 58, 59, 60, 63 

Van Dyke, 42 

van ITelmont, J. B., 11, 12 

van Hisc, C. R., 22 

Van Slyke, T.. L., 254 

Venable, C. S., 47 

Vencl, Fr., 12 

Verschaffelt, J. E., 59, 77, 79 

Villard, P., 58, 59, 108, 113 

von Hammel, A., 103 

v. Lude, K., 66 

von Obermaycr, A., 45 

v. Siemens, H., 63 

Von Wesendonck, 59 

Voorhees, G. T., 198 

Wagner, II., 137 
Wahl, W., 80 
Waitz, 45 

Waledinsky, J. A., 142 
Walker, A. C, 154 
Walker, G. W., 80, 81 
Walker, J., 118 
Walker, W. H., 148, 158 
Warburg, E., 41 
Waters, R. M., 141 
Wattenberg, H., 119 
Weber, S., 61, 63 
Wender, 28 



290 



AUTHOR INDEX 



West, C, 260 
Wheeler, 133 
White, H. L,., 137 
Whitman, W. G., 157, 160, 161 
Wiedetnann, H., 35 
Wilke, E., 114 
Williams, W. C, 20 
Williamson, E. D., 122, 123 
Williamson, R. V., 160, 167 
Windhausen, F., 198 
Wismer, K. I-., 108 
Woodhouse, J. C., 87, 88, 91 
Woodroof, J. G. f 246 



Woodruff, J. C., 189 
Wrede, F. J., 35 
Wroblewski, S., 95, 113 
Wyatt, K. S., 108 
Wuller, A., 42 

Yamasaki, K., 130 
Yammamoto, T., 49 
Youkov, G. I., 30 
Younff, H. D., 144 

Zcleny, 58 
Zumbro, F. R., 198 



Subject Index 



Absorbers, bubble-plate towers, 165 

coke towers, 164, 166 

efficiency of, 166 
Absorption, in alkali carbonates, 153 

cliff usional coefficients in, 158 

effect of viscosity on rate of, 161 

effect of sulfates on, 162 

experiments on, 159 

in colloidal solutions, 161 

in mpnoethanolamine, 153 

in triethanolamine, 152 

in water, 151 

mechanism of, 157 

rate of, 161 

Acidity control with CO 2f 265 
Adsorption, 81, 151, 174 

equilibrium relations of, 154 

heat of, 92 

on Acheson graphite, 90 

on alumina, 90 

on Ceylon graphite, 90 

on charcoal, 85 

on manganese dioxide, 89 

on metallized silica gel, 89 

on silica gel, 82, 93 

on silver, 90 

on SnO 2 , TiO 2 , 90 

Airplane starting, use of liquid CO 2 , 253 
Airship inflation, use of C<X 268 
Alkaline earth silicates, action of CO 3 
solutions, 127 

solubility in CO ? solutions, 127 
Aluminum alloy rivets, chilling, 241 
Anesthesia, 141 

Anesthetics, administration of, 140 
Animals, physiological effect of CO a on, 
139 

respiratory stimulation of, 139 
Atmosphere, CO a concentration in, 19, 29 

composition of, 13 

Backus process for purification of CO a , 185 
Baths, carbonated, 142 

dry CO 2 , 142 

Beattie and Bridgeman equation, 57 
Beer, raising, 253 
Beet sugar refining, 266 
Bell buoys, power for operation of, 252 
Bell Telephone Company, use of liquid 

CO, for fire extinguishing, 254 
Beverages, carbonating, 254 
Blasting with liquid CO a , 248 
Brewing, by-product CO ? in, 184 
Bunsen absorption coefficient a, 94, 97 



Burgbrohl wells, 18 
Butanol, manufacture of, 188 

Cables, drying and testing, 268 

Cailletet apparatus, 96 

Calcite, solubility, ion concentration, 123 

temperature coefficient of solubility, 124 
Calcium compounds, reaction with car- 
bonic acid, 121 

bicarbonate, formation of, 122 

carbonate, solubility in water solutions 
of CO 2 , 122 

cyanamide, action of CO a on, 126 

phosphate, action of CO a on, 126 

phosphate (secondary), solubility, 127 

sulfide, action of CO a on, 126 
Canning industry, use of CO 2 , 264 
"Carbogen," 140 
"Carboleum," 17 

Carbon, reduction of CO a by, 132 
Carbon dioxide, as inert gas, 265 

commercial uses, 230 

compressibility, 50 

decomposition, 131 

dehydration, 172 

density, 34 

diffusion through solids, 46 

equation of state, 54 

history, 11 

hydrates, 113 

in nature, 19, 29 

manufacture of, 14, 27 

mean free path, 41 

molecular diameter, 40 

molecular velocity, 41 

molecular volume, 40 

molecular weight, 40 

physical properties, 34 

purification, 172 

uses, 254 

viscosity, 41 

wells, in Germany, 18 
in Italy, 27 
in Mexico, 28 
in Utah, 28 
Carbon dioxide, liquid, 16, 18 

as power producer, 252 

as a solvent, 108 

blasting, 248 

compressibility, 52 

condensers, 177 

density, 35 

dielectric constant, 79 

enthalpy, 76 



291 



292 



SUBJECT INDEX 



Carbon dioxide, liquid (continued) 
entropy, 77 
manufacture, 146 

absorption in, 151 

fuel, used in, 147 

furnace, used, 146 

scrubbers, used, 150 
molal heat capacity, 68 
production, 246 
specific volume, 57 
surface tension, 77 
surface tension curve, 79 
uses, 248 

vapor pressure, 61 
Carbon dioxide, solid, 15, 28, 193 
crystals of, 79 
density, 39 
enthalpy, 76 

equilibrium systems with solvents, 112 
formation, 206 

freezing to stop flow in pipes, 244 
freezing histological specimens, 243 
laboratory uses, 242 
manufacture, 203 

Agcfko process, 218 

Carba process, 213 

Carbice machine, 210 

Dry Ice Corporation, 207 

Esslingen apparatus, 219 

Linde-Surth process, 218 

Maiuri process, 220 

Pegna apparatus, 219 

presses, horizontal, 209 

presses, vertical, 212 

snow tank, 207 

Solid Carbonic Co., Ltd., 210 
marketing, 194 
melting point, 60 
molal heat capacity, 68 
odor removal, 205 
rain making, 247 
refrigeration, 230 
shrinkage by means of, 240 
specific volume, 57 
storage, economic problems, 225 

engineering, 226 

structures, 227 

trade problems, 226 
structure, 205 
transportation losses, 223 

truck, 222 

use as an escharotic, 141 
vapor pressure, 61 
water removal, 204 
Carbon dioxide- water system, 117 
Carbon monoxide, 132, 140 
Carbonated baths, 142 
Carbonates, CO., from, 179 

manufacture of, 264 
Carbonic acid, 114, 265 
calcium compounds, reaction, 121 
dissociation constant, 116 
magnesium compounds, reaction, 128 



Cardox blasting equipment, 248 

Cement, see Portland Cement 

Cement kilns, 180 

Charcoal adsorption, 85 

Chemical control by means of CO 2 , 268 

Chemical industry, use of CO 3 , 264 

Chlorpicrin, 244 

Clausius-Clapeyron equation, 69, 93 

Coal mines, blasting, 251 

Cockroach, effect of CO 2 on, 144 

Coefficient of diffusion, 45 

of thermal expansion, 55 
Coke process, 18 
Combustion, chemistry of, 148 
Compressors, 16 

lubrication, 175 

oil removal, 176 
Condensers, steam, 171 
Corrosion by CO 2 , 204 
Critical pressure, 59 
Critical temperature, 59 
Crystal Carbonic Laboratory, 181 

Dementia praecox catatonia, effect of 

CO 2 , 141 
Dermatologic affections, treatment of, 

141 

Desorption, theory of, 170 
Dielectric constant, 79 
Diffusion equation, 31 
Dissociation at high temperatures, 64 
Dolomite, 181 
Dry Ice Corporation, 207 

Eggs, preservation, 261 

Enthalpy, 71 

Entropy, 76 

Equation of state, 54 

Equilibrium diagram, 63 

Escharotic, use of solid CO 2 as an, 141 

Fermentation by product CO 2 , 182 

purification, 185 
Fermentation process, 183 
Fertilization, direct, 136 

indirect, 138 
Fertilizers, 138 
Film, drying of, 265 
Fire extinguishers, 17, 255 
"Fixed air," 12 
Flowers, preservation, 261 
Flue gas, 148 

Food products, freezing, 246 
Foods, preservation, 260 
Freezing point, 60 
Fruit juices, removal of sulfur dioxide, 

265 

Fruits, preservation, 260 
Fruits, vegetables and flowers, effects of 

CO 2 , 262 

Fumigation of foods, 144 
Fur preservation, 145 
Fusion, heat of, 70 



SUBJECT INDEX 



293 



Gas, natural, sec Natural gas 
Gasometers, 172 

Gillette Research Corporation manufac- 
turing process, 180 
Golf balls, chilling, 245 
Grotta del Cane, 24 

Henry's law, 91, 114, 158 
Henry's law constant, 95 
Hiccough, treatment of, 141 
Histology, use of solid COj, 243 
Hydrogen, reduction of CO a by, 131 

Igneous rocks, 24 

Infantile tetany, treatment of, 141 

Insanity, effect of CO., 141 

Insecticides, 144 

Isenthalpic values, 72 

Isothermal and isoharic values of /A, 74 

Java, volcanic gases, 25 
Joule-Kelvin effect, 71 
Joule-Thompson effect, 71 

Kiel, 17 

Kolbe synthesis, 264 

Kohlensaure- Werke, 1 8 

Krupp Steel Works, 17 

Kuenen absorption coefficient, 94 

Laacher Lake, 25 

Lay torpedo, 1(> 

Lead acetate, aqueous solutions, action of 

CO* 129 

Leaks, testing, 253 
Lethal effect of CO., 139 
Lindc-Siirth process, 178 
Liquefaction, 14, 175 
Liquefying apparatus, 15 
Loschmidt-von Obermayer equation, 45 
Lubricating oil, solubility in liquid CO,, 

109 - 
Lye boiling, 167 

Machine parts, shrinkage, 240 
Magnesium carbonate, molal concentra- 
tion, 128 

solubility in CO 2 solutions, 128 
Magnesium compounds, reaction with 

carbonic acid, 128 
Meat and fish, preservation, 261 
Metabolism, 136 
Metals, reaction with CO Jt 133 
Methanol manufacture, 152 
Mineral water, 18 
Molecular heat capacity, 64 
Moths, effect of CO a on, 145 

Narcotic effect of CO 2 , 139 
Natural gas, 149 

Manitou, Colorado, 28 
Natural waters, 124 



Ostwald solubility expression 1, 94 

Paint guns, 253 
Patents list of 
applications of solid CO 2 , 276 

Austria, 276 

France, 276 

Germany, 276 

Great Britain, 276 

United States, 276 

manufacture, methods and apparatus, 
272 

Austria, 273 

Belgium, 273 

Brazil, 273 

Canada, 274 

Cuba, 274 

Czccho-Slovakia, 274 

France, 274 

Germany, 275 

Great B'ritain, 273, 274 

Hungary, 275 

Italy, 275 

Japan, 275 

Switzerland, 275 

United States, 272 
storage and transportation, 277 

Germany, 277 

Great Britain, 277 

Switzerland, 277 

United States, 277 
vaporizing of solid CO.., 277 

France, 277 

Germany, 277 

Great Britain, 277 

Switzerland, 277 

United States, 277 
pH of water solutions of CO.,, 119 
Photosynthesis, 31 
Phthalic anhydride distillation, 265 
Physiological effects of CO.,, 136 
Plank and Kuprianoff equation, 56 
Plant growth, stimulation of by CO.,, 136 
Pneumonia, effect of CO,, 140 
Portland cement, hardening, 268 
Potassium hircarbonate, see Potassium 

carbonate 
Potassium carbonate, concentrations, 156 

equilibrium conditions, 156 
Power bottle, 252 
"Prcst-air" power bottle, 252 
Purification, 172 

absorption and chemical treatment, 187 
Backus process, 185 
Reich process, 186 
Pyrmont, water, 12, 13, 14 

Railway signals, 252 

Raoult absorption coefficient, 94 

Reduction of CO., by carbon, 132 

hydrogen, 131 
Refraction, index of, 80 
Refrigerating machines, 18 



294 



SUBJECT INDEX 



Refrigeration, binary cycle, 201 

bleeder cycle, 198 

bleeder-precooling cycle, 199 

cycles, 196 

carbon dioxide, solid, 230 

ice cream dispensing equipment, 234 

meat and fish, 237 

mechanical, 248 

package, 232 

power consumption, 203 

precooling cycle, 198 

pressure snow-making cycle, 199 

railroad, 237 

simple cycle, 196 

stoppages, 205 

truck, 233 

Refrigerator cars, 237 
Rocks, weathering, 32 
Roth equation, 46 

Rubber, CO, diffusion through, 49 
Rubber industry, use of CO 2 , 267 

Scale removal, 267 
Schwalback source of CO 2 , 14 
Scrubbers, 150 
Sea water, CO 2 content, 22 

CO 2 equilibrium, 119 
Seltz water, 12, 13 
Silica gel adsorption, 82, 93 
Skin diseases, treatment with solid CO 2 , 

141 

Sodium bicarbonate process, 17 
Sodium sulfide, action of CO a on, 126 
Soil respiration, 31 
Solubility, 94 

carbon compounds, 102 

effect of temperature, 94 

effect of temperature and pressure 
changes, 96 

ethyl alcohol, 104 

inorganic compounds, 98 

organic solvents, 104 

water solutions of inorganic com- 
pounds, 97 

Sound, velocity of in CO 2 , 41 
Spa mineral water, 13 
Specific heat, 67 
Specific volume, 57 
Spring, brine, Bavaria, 27 
Springs, carbonated, 26 

Altwasser, 26 

Auvergne, 26 

Hot Springs, (Va.), 26 

Manitou, (Colo.), 26 



Springs, carbonated (continued) 

Napa Soda Springs, 26 

Pyrmont, 26 

Reinerz, 26 

Salzbrunn, 26 

Saratoga Springs, 26, 28 

Seltzer, 26 

Vivarais, 26 
Starch, hydration action of carbonic 

acid, 131 

Steel, cold treatment, 242 
Stefan-Maxwell equation, 45 
Storage, 189 
Sublimation, heat of, 69 
Supersaturation, liquids, 106 

water solutions, 107 

equation, 107 
Siirth system, 177 
Sutherland equation, 42 

Tables, list of, 271 

physical data, 278 
Therapeutics, use of CO 2 , 140 
Thilorier liquefying apparatus, 15 
Throttling effect, 71 
Tillman equation, 125 
Transportation, 189 
Triple point, 57 
Tunguragua a source of CO 2 , 24 

U. S. Industrial Alcohol Co., 185 
Urea, manufacture of, 134 

van der Waal's equation, 54 
Vaporization, latent heat of, 68 
Viscosity, 41 
Volcanic gases, 24 
analysis, 24 

Water, acidity of solutions of CO 2 , 119 

CO 2 content, 124 

reaction with CO 2 , 113 

system carbon dioxide- water, 117 
Water pipes, cleaning, 267 
Water supplies, carbonation of, 266 
Wells, cleaning, 253 
Whooping cough, treatment of, 141 

Yellowstone National Park, springs, boil- 
ing, 27 

Stygian caves a source of CO 2 , 25 
Young's equation, 61 

Zinc oxide, 265 



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American Chemical Society 

MONOGRAPH SERIES 



PUBLISHED 

No. 

1. The Chemistry of Enzyme Action (Revised Edition) 

By K. George Falk. 

2. The Chemical Effects of Alpha Particles and Electrons 

(Revised Edition) 
By Samuel C. Lind. 

3. Organic Compounds of Mercury 

By Frank C. Whitmore. (Revision in preparation) 

4. Industrial Hydrogen 

By Hugh S. Taylor. 

5. Zirconium and Its Compounds 

By Francis P. Vcnablc. 

6. The Vitamins (Revised Edition) 

By H. C. Sherman and S. L. Smith. 
7. The Properties of Electrically Conducting Systems 

By Charles A. Kraus. 
8. The Origin of Spectra 

By Paul IX Foote and F. L. Mohler. (Revision in prepa- 
ration) 

9. Carotinoids and Related Pigments 
By Leroy S. Palmer. 

10. The Analysis of Rubber 

By John B. Tuttlc. 

11. Glue and Gelatin 

By Jerome Alexander. (Revision in preparation) 

12. The Chemistry of Leather Manufacture (Revised Edition) 

By John A. Wilson. Vol. I and Vol. II. 

13. Wood Distillation 

By L. F. Hawley 

14 Valence and the Structure of Atoms and Molecules 

By Gilbert N. Lewis. (Revision in preparation) 

15. Organic Arsenical Compounds 

By George W. Raiziss and Jos. L. Gavron. 

16. Colloid Chemistry (Revised Edition) 
By The Svedberg. 

17, Solubility (Revised Edition) 
By Joel H. Hildebrand. 

18. Coal Carbonization 

By Horace C. Porter. (Revision in preparation) 

19. The Structure of Crystals (Second Edition) and Supple- 

ment to Second Edition 
By Ralph W. G. Wyckoff. 

20. The Recovery of Gasoline from Natural Gas 

By George A. Burrell. 

21. The Chemical Aspects of Immunity (Revised Edition) 

By H. Gideon Wells. 

22. Molybdenum, Cerium and Related Alloy Steels 

By H. W. Gillett and E. L. Mack. 

23. The Animal as a Converter of Matter and Energy 

By H. P. Armsby and C. Robert Motilton. [Continued] 



American Chemical Society 

MONOGRAPH SERIES 

PUBLISHED 

No. 

24. Organic Derivatives of Antimony 

By Walter G. Christiansen. 

25. Shale Oil 

By Ralph IT. McKee. 

26. The Chemistry of Wheat Flour 

By C. H. Bailey. 

27. Surface Equilibria of Biological and Organic Colloids 

By P. Lecomte du Noiiy. 

28. The Chemistry of Wood 

By L. F. Hawley and Louis E. Wise. 

29. Photosynthesis 

By H. A. Spoehr. 

30. Casein and Its Industrial Applications 

By Edwin Sutermeister. To be revised by F. L. Browne. 

31. Equilibria in Saturated Salt Solutions 

By Walter C. Blasdale. 

'32. Statistical Mechanics as Applied to Physics and Chemistry 
By Richard C. Tolman. (Revision in preparation) 

33. Titanium 

By William M. Thornton, Jr. 

34. Phosphoric Acid, Phosphates and Phosphatic Fertilizers 

By W. H. Waggaman. 

35. Noxious Gases 

By Yandell Henderson and H. W. Haggard. 

36. Hydrochloric Acid and Sodium Sulfate 

By N. A. Laury. 

37. The Properties of Silica 

By Robert B. Sosman. 

38. The Chemistry of Water and Sewage Treatment 

By Arthur M. Buswell. (Revision in preparation) 

39. The Mechanism of Homogeneous Organic Reactions 

By Francis O. Rice. 

40. Protective Metallic Coatings 

By Henry S. Rawdon. To be revised by H. M. Burns. 

41. Fundamentals of Dairy Science (Revised Edition) 

By Associates of Rogers. 

42. The Modern Calorimeter 

By Walter P. White. 

43. Photochemical Processes 

By George B. Kistiakowsky. 
44. Glycerol and the Glycols 
By James W. Lawrie. 

45. Molecular Rearrangements 

By C. W. Porter. 

46. Soluble Silicates in Industry 

By James G. Vail. 

47. Thyrozine 

By E, C. Kendall. [Continued] 



American Chemical Society 

MONOGRAPH SERIES 

PUBLISHED 

No. 

48. The Biochemistry of the Amino Acids 

By H. H. Mitchell and T. S. Hamilton. 

49. The Industrial Development of Searles Lake Brines 

By John E. Tecple. 

50. The Pyrolysis of Carbon Compounds 

By Charles D. Hurd. 

51. Tin 

By Charles L. Mantcll. 

52. Diatomaceous Earth 

By Robert Calvcrt. 

53. Bearing Metals and Bearings 

By William M. Corse. 

54. Development of Physiological Chemistry in the United 

States 

By Russell H. Chittenden. 

55. Dielectric Constants and Molecular Structure 
By Charles P. Smyth. 

56. Nucleic Acids 

By P. A. Levene and L. W. Bass. 

57. The Kinetics of Homogeneous Gas Reactions 

By Louis S. Kassel. 

58. Vegetable Fats and Oils 

By George S. Jamieson. 

59. Fixed Nitrogen 

By Harry A. Curtis. 

60. The Free Energies of Some Organic Compounds 

By G. S. Parks and H. M. Huffman. 

61. The Catalytic Oxidation of Organic Compounds in the Vapor 

Phase 

By L. F. Marek and Dorothy A. Hahn. 
62. Physiological Effects of Radiant Energy 
By H. Laurens. 

63. Chemical Refining of Petroleum 

By V. Kalichevsky and B. A. StaRncr. 

64. Therapeutic Agents of the Quinoline Group 

By W. F. Von Oettingen. 

65. Manufacture of Soda 

By T. P. Hou. 

66. Electrokinetic Phenomena and Their Application to Biology 

and Medicine 
By H. A. Abramson. 

67. Arsenical and Argentiferous Copper 

By J. L. Gregg. 

68. Nitrogen System of Compounds 

By E. C. Franklin. 

69. Sulfuric Acid Manufacture 

By Andrew M. Fairlie. 

70. The Chemistry of Natural Products Related to Phenan- 

threne 
By L. F. Fieser. t 

71. The Corrosion Resistance of Metals and Alloys 

By Robert J. McKay and Robert Worthington. 



American Chemical Society 

MONOGRAPH SERIES 

IN PREPARATION 

Piezo-Chemistry 

By L. H. Adams. 
Water Softening 

By A. S. Behrman. 
The Biochemistry of the Fats and Related Substances 

By W. R. Bloor. 
Polymerization 

By R. E. Burk. 
Absorptive Carbon 

By N. K. Chancy. 
Surface Energy and Colloidal Systems 

By W. D. Harkins and T. F. Young. 

Significance of Manganese, Iron and Aluminum to Soil Acidity 
and Plant Life 

By Forman T. McLean. 
Physical and Chemical Properties of Glass 

By George W. Morey. 
Metabolic Action of Insulin 

By John R. Murlin. 
Acetylene 

By J. A. Nieuwland. 
Furfural and other Furan Compounds 

By F. N. Peters, Jr., and H. J. Brownlce. 
Aliphatic Sulfur Compounds 

By E. Emmet Reid. 
The Chemistry of Intermediary Metabolism 

By Wm. C. Rose. 
Electrical Precipitation of Suspended Particles from Gases 

By W. A. Schmidt and Evald Anderson. 
Mineral Metabolism 

By A. T. Shohl. 
Precise Electric Thermometry 

By W. P. White and E. F. Mueller. 
Ergosterol 

By A. Windaus. 
Measurement of Particle Size and Its Application 

By L. T. Work. 

A Study of Amino Acids, Proteins and Related Substances 
By Edwin J. Cohn. 

Raw Materials of Lacquer Manufacture 
By J. S. Long.